How do I make the first letter of a string uppercase in JavaScript?

Question

How do I make the first character of a string uppercase if it's a letter, but not change the case of any of the other letters?

For example:

• "this is a test" → "This is a test"
• "the Eiffel Tower" → "The Eiffel Tower"
• "/index.html" → "/index.html"

• Aaron: Underscore has a plugin called underscore.string that includes this and a bunch of other great tools.
• ecstrema: For those using angular, there is a titlecase pipe: angular.io/api/common/TitleCasePipe
• mickmackusa: For those who don't know how Stack Overflow is designed to work: Resolving advice is posted to the page as an "answer". Any non-resolving advice, requests for clarity, and lone/relevant hyperlinks can be posted as comments under the question.

Answer 1

function capitalizeFirstLetter(val) {
 return String(val).charAt(0).toUpperCase() + String(val).slice(1);
}

Some other answers modify String.prototype (this answer used to as well), but I would advise against this now due to maintainability (hard to find out where the function is being added to the prototype and could cause conflicts if other code uses the same name/a browser adds a native function with that same name in future).

• Dan Tello: Here's this solution in TypeScript, where the type returned is the capitalized word, rather than string: const capitalize = <T extends string>(s: T) => (s[0].toUpperCase() + s.slice(1)) as Capitalize<typeof s>;
• Lukas Kalbertodt: This is mentioned in answers below, but worth pointing out here: this answer does not work for all Unicode text. Passing "𐐨𐑍𐑏" to this function returns the same string, but it should return "𐐀𐑍𐑏". That's because charAt splits at UTF16 code units. There are characters with case-folding definitions in the SMP that are encoded with two UTF16 code units. While simple, this shouldn't be used.
• Lukas Kalbertodt: You don't even have to reach for rare languages to break this. Unicode ligature characters break this as well: "flat" is returned as "FLat".
• mhvelplund: @Disorder it's not a launguage feature. Dan just defines the function as a type-safe one-liner ... not super useful?
• Disorder: @mhvelplund just mentioned that Capitalize type in TS is a key for typing, and it's out of the box. What's wrong? typescriptlang.org/docs/handbook/…

Answer 2

Edited to add this DISCLAIMER: please read the comments to understand the risks of editing JS basic types.

---

Here's a more object-oriented approach:

Object.defineProperty(String.prototype, 'capitalize', {
 value: function() {
 return this.charAt(0).toUpperCase() + this.slice(1);
 },
 enumerable: false
});

You'd call the function, like this:

"hello, world!".capitalize();

With the expected output being:

"Hello, world!"

• aggregate1166877: @NielsLucas Fair enough. It has the potential to break future additions to JS. If it's code that only you will use, then it's not so bad - you just update your code and move on. The real issue here is when you start publishing libraries with code like this: your code modifies the built-in behavior for every library using your code. The consequence is that if you and another library author both override the same built-ins with your own implementations, you create bugs in the other library's code (or whichever is loaded last) leaving the user with debugging hell of unreproducible bug reports.
• Niels Lucas: @aggregate1166877 Thank you for the explanation. I totally agree with you that this way is NOT gonna be a good practice for creating a library and I also agree that this way is fine for a project. Hope people will read this, cause I think this is a good attention to the original answer.
• Martijn Scheffer: sorry but no, just don't add any functions to basic types. extend them ? const ExtendedString = class extends String { capitalize () { return this[0].toUpperCase() + this.slice(1) } } const s = new ExtendedString('hello') console.log(s.capitalize())
• vir us: if I ever add custom functions like that, my approach is to add unique scope to the names of such methods. Like for example if your project name is MyProject then it would be "hello world".myProjectCapitalise() or something along those lines. So if something external changes, it won't clash with that name. Just need to make sure the scope is unique enough in your context.
• vir us: @VLAZ, ok I was wrong. Your proposed solution with Symbols indeed suits. let capitalizeSym = Symbol('capitalize') String.prototype[capitalizeSym] = function (...){...} - this avoids potential collisions due to how Symbol works. However one have to keep global reference to capitalizeSym in order to access the function later on which is not ideal neither. In most cases people would be fine with the original answer above anyways, considering the caveats. I didn't know much about Symbols though but learned something new thanks to your comment.

Answer 3

Using just CSS and its text-transform property:

p::first-letter {
 text-transform: capitalize;
}

• DonMB: $('#mystring_id').text(string).css('text-transform','capitalize')
• dmansfield: Additionally, this only affects the display of the string - not the actual value. If it's in a form, e.g., the value will still be submitted as-is.
• Dzmitry Kulahin: Also ::first-letter works ONLY on elements with a display value of block, inline-block, table-cell, list-item or table-caption. In all other cases, ::first-letter has no effect.
• Leland: ^ I am immensely curious why this doesn't work for flex and grid....
• mikakun: not everything in a html page can be formatted with css. like title property for example. therefore you're not answering at all the question !

Answer 4

Here is a shortened version of the popular answer that gets the first letter by treating the string as an array:

function capitalize(s)
{
 return String(s[0]).toUpperCase() + String(s).slice(1);
}

Update

According to the comments below this doesn't work in IE 7 or below.

Update 2:

To avoid undefined for empty strings (see @njzk2's comment below), you can check for an empty string:

function capitalize(s)
{
 return s && String(s[0]).toUpperCase() + String(s).slice(1);
}

ES6 version

const capitalize = s => s && String(s[0]).toUpperCase() + String(s).slice(1)
// to always return type string event when s may be falsy other than empty-string
const capitalize = s => (s && String(s[0]).toUpperCase() + String(s).slice(1)) || ""

• rsedlr: To always return a string, I find s ? s[0].toUpperCase() + s.slice(1) : "" more readable
• Timo: If you have a string from an object, use e.g. elem.name[0].toUpperCase() + elem.name.slice(1)
• Timo: Likely unrelated to your answer, but why do you offer a one-line function for the short code? Remembering string manipulation is what we should train to keep the brain busy.

Answer 5

I didn’t see any mention in the existing answers of issues related to (削除) astral plane code points or (削除ここまで) internationalization. "Uppercase" doesn’t mean the same thing in every language using a given script.

Initially I didn’t see any answers addressing issues related to astral plane code points. There is one, but it’s a bit buried (like this one will be, I guess!)

Overview of the hidden problem and various approaches to it

Most of the proposed functions look like this:

function capitalizeFirstLetter(str) {
 return str[0].toUpperCase() + str.slice(1);
}

However, some cased characters fall outside the BMP (basic multilingual plane, code points U+0 to U+FFFF). For example take this Deseret text:

capitalizeFirstLetter("𐐶𐐲𐑌𐐼𐐲𐑉"); // "𐐶𐐲𐑌𐐼𐐲𐑉"

The first character here fails to capitalize because the array-indexed properties of strings don’t access "characters" or code points*. They access UTF-16 code units. This is true also when slicing — the index values point at code units.

It happens to be that UTF-16 code units are 1:1 with USV (Unicode scalar value) code points within two ranges, U+0 to U+D7FF and U+E000 to U+FFFF inclusive. Most cased characters fall into those two ranges, but not all of them.

From ES2015 on, dealing with this became a bit easier. String.prototype[@@iterator] yields strings corresponding to code points**. So for example, we can do this:

function capitalizeFirstLetter([ first='', ...rest ]) {
 return [ first.toUpperCase(), ...rest ].join('');
}
capitalizeFirstLetter("𐐶𐐲𐑌𐐼𐐲𐑉") // "𐐎𐐲𐑌𐐼𐐲𐑉"

For longer strings, this is probably not terribly efficient*** — we don’t really need to iterate the remainder. We could use String.prototype.codePointAt to get at that first (possible) letter, but we’d still need to determine where the slice should begin. One way to avoid iterating the remainder would be to test whether the first codepoint is outside the BMP; if it isn’t, the slice begins at 1, and if it is, the slice begins at 2.

function capitalizeFirstLetter(str) {
 if (!str) return '';
 const firstCodePoint = str.codePointAt(0);
 const index = firstCodePoint > 0xFFFF ? 2 : 1;
 return String.fromCodePoint(firstCodePoint).toUpperCase() + str.slice(index);
}
capitalizeFirstLetter("𐐶𐐲𐑌𐐼𐐲𐑉") // "𐐎𐐲𐑌𐐼𐐲𐑉"

You could use bitwise math instead of > 0xFFFF there, but it’s probably easier to understand this way and either would achieve the same thing.

We can also make this work in ES5 and below by taking that logic a bit further if necessary. There are no intrinsic methods in ES5 for working with codepoints, so we have to manually test whether the first code unit is a surrogate****:

function capitalizeFirstLetter(str) {
 if (!str) return '';
 var firstCodeUnit = str[0];
 if (firstCodeUnit < '\uD800' || firstCodeUnit > '\uDFFF') {
 return str[0].toUpperCase() + str.slice(1);
 }
 return str.slice(0, 2).toUpperCase() + str.slice(2);
}
capitalizeFirstLetter("𐐶𐐲𐑌𐐼𐐲𐑉") // "𐐎𐐲𐑌𐐼𐐲𐑉"

Deeper into internationalization (whose capitalization?)

At the start I also mentioned internationalization considerations. Some of these are very difficult to account for because they require knowledge not only of what language is being used, but also may require specific knowledge of the words in the language. For example, the Irish digraph "mb" capitalizes as "mB" at the start of a word. Another example, the German eszett, never begins a word (afaik), but still helps illustrate the problem. The lowercase eszett ("ß") capitalizes to "SS," but "SS" could lowercase to either "ß" or "ss" — you require out-of-band knowledge of the German language to know which is correct!

The most famous example of these kinds of issues, probably, is Turkish. In Turkish Latin, the capital form of i is İ, while the lowercase form of I is ı — they’re two different letters. Fortunately we do have a way to account for this:

function capitalizeFirstLetter([ first='', ...rest ], locale) {
 return [ first.toLocaleUpperCase(locale), ...rest ].join('');
}
capitalizeFirstLetter("italy", "en") // "Italy"
capitalizeFirstLetter("italya", "tr") // "İtalya"

In a browser, the user’s most-preferred language tag is indicated by navigator.language, a list in order of preference is found at navigator.languages, and a given DOM element’s language can be obtained (usually) with Object(element.closest('[lang]')).lang || YOUR_DEFAULT_HERE in multilanguage documents.

In agents which support Unicode property character classes in RegExp, which were introduced in ES2018, we can clean stuff up further by directly expressing what characters we’re interested in:

function capitalizeFirstLetter(str, locale=navigator.language) {
 return str.replace(/^\p{CWU}/u, char => char.toLocaleUpperCase(locale));
}

This could be tweaked a bit to also handle capitalizing multiple words in a string with fairly good accuracy for at least some languages, though outlying cases will be hard to avoid completely if doing so no matter what the primary language is.

The \p{CWU} or Changes_When_Uppercased character property matches all code points which change when uppercased in the generic case where specific locale data is absent. There are other interesting case-related Unicode character properties that you may wish to play around with. It’s a cool zone to explore but we’d go on all day if we enumerated em all here. Here’s something to get your curiosity going if you’re unfamiliar, though: \p{Lower} is a larger group than \p{LowercaseLetter} (aka \p{Ll}) — conveniently illustrated by the default character set comparison in this tool provided by Unicode. (NB: not everything you can reference there is also available in ES regular expressions, but most of the stuff you’re likely to want is).

Alternatives to case-mapping in JS (Firefox & CSS love the Dutch!)

If digraphs with unique locale/language/orthography capitalization rules happen to have a single-codepoint "composed" representation in Unicode, these might be used to make one’s capitalization expectations explicit even in the absence of locale data. For example, we could prefer the composed i-j digraph, ij / U+133, associated with Dutch, to ensure a case-mapping to uppercase IJ / U+132:

capitalizeFirstLetter('ijsselmeer'); // "IJsselmeer"

On the other hand, precomposed digraphs and similar are sometimes deprecated (like that one, it seems!) and may be undesirable in interchanged text regardless due to the potential copypaste nuisance if that’s not the normal way folks type the sequence in practice. Unfortunately, in the absence of the precomposition "hint," an explicit locale won’t help here (at least as far as I know). If we spell ijsselmeer with an ordinary i + j, capitalizeFirstLetter will produce the wrong result even if we explicitly indicate nl as the locale:

capitalizeFirstLetter('ijsselmeer', 'nl'); // "Ijsselmeer" :(

(I’m not entirely sure whether there are some such cases where the behavior comes down to ICU data availability — perhaps someone else could say.)

If the point of the transformation is to display textual content in a web browser, though, you have an entirely different option available that will likely be your best bet: leveraging features of the web platform’s other core languages, HTML and CSS. Armed with HTML’s lang=... and CSS’s text-transform:..., you’ve got a (pseudo-)declarative solution that leaves extra room for the user agent to be "smart." A JS API needs to have predictable outcomes across all browsers (generally) and isn’t free to experiment with heuristics. The user-agent itself is obligated only to its user, though, and heuristic solutions are fair game when the output is for a human being. If we tell it "this text is Dutch, but please display it capitalized," the particular outcome might now vary between browsers, but it’s likely going to be the best each of them could do. Let’s see:

<!DOCTYPE html>
<dl>
<dt>Untransformed
<dd>ijsselmeer
<dt>Capitalized with CSS and <code>lang=en</code>
<dd lang="en" style="text-transform: capitalize">ijsselmeer
<dt>Capitalized with CSS and <code>lang=nl</code>
<dd lang="nl" style="text-transform: capitalize">ijsselmeer

In Chromium at the time of writing, both the English and Dutch lines come out as Ijsselmeer — so it does no better than JS. But try it in current Firefox! The element that we told the browser contains Dutch will be correctly rendered as IJsselmeer there.

This solution is purpose-specific (it’s not gonna help you in Node, anyway) but it was silly of me not to draw attention to it previously given some folks might not realize they’re googling the wrong question. Thanks @paul23 for clarifying more about the nature of the IJ digraph in practice and prompting further investigation!

---

As of January 2021, all major engines have implemented the Unicode property character class feature, but depending on your target support range you may not be able to use it safely yet. The last browser to introduce support was Firefox (78; June 30, 2020). You can check for support of this feature with the Kangax compat table. Babel can be used to compile RegExp literals with property references to equivalent patterns without them, but be aware that the resulting code can sometimes be enormous. You probably would not want to do this unless you’re certain the tradeoff is justified for your use case.

---

In all likelihood, people asking this question will not be concerned with Deseret capitalization or internationalization. But it’s good to be aware of these issues because there’s a good chance you’ll encounter them eventually even if they aren’t concerns presently. They’re not "edge" cases, or rather, they’re not by-definition edge cases — there’s a whole country where most people speak Turkish, anyway, and conflating code units with codepoints is a fairly common source of bugs (especially with regard to emoji). Both strings and language are pretty complicated!

---

* The code units of UTF-16 / UCS2 are also Unicode code points in the sense that e.g. U+D800 is technically a code point, but that’s not what it "means" here ... sort of ... though it gets pretty fuzzy. What the surrogates definitely are not, though, is USVs (Unicode scalar values).

** Though if a surrogate code unit is "orphaned" — i.e., not part of a logical pair — you could still get surrogates here, too.

*** maybe. I haven’t tested it. Unless you have determined capitalization is a meaningful bottleneck, I probably wouldn’t sweat it — choose whatever you believe is most clear and readable.

**** such a function might wish to test both the first and second code units instead of just the first, since it’s possible that the first unit is an orphaned surrogate. For example the input "\uD800x" would capitalize the X as-is, which may or may not be expected.

• Stephan Bijzitter: I had been wondering for a while why toUpperCase didn't really do much for some languages... but didn't quite care enough to find out. Glad I finally did, this was a very interesting read!
• paul23: This doesn't seem to work with digraphs such as "IJ" in dutch. Using the latest version the example here is incorrectly capitalized to "Ijsselmeer" (The regex version). The code I used was: capitalizeFirstLetter('ijssel', 'nl-NL') - That's a correct localization string right?
• paul23: In netherlands dutch IJ is considered 2 letters, which are just capitalized at the same time (in contrary to the belgian version).
• Lukas Kalbertodt: Great answer! Quite embarrassing how many broken answers exist here. I would recommend adding a small "tl;dr" section at the very top.
• Semicolon: @GéryOgam It may be helpful to know the formal term for what you’re trying to do with the second regular expression in the answer you linked: "segmentation". Segmentation is complex and, in some cases, its behavior varies with language as well. It’s defined by UAC #29. Fortunately, ECMAScript (via ECMA-402, the Intl API) provides an API for this, %Intl.Segmenter%. You’d use granularity: "word".

Answer 6

If you're interested in the performance of a few different methods posted:

Here are the fastest methods based on this jsperf test (ordered from fastest to slowest).

As you can see, the first two methods are essentially comparable in terms of performance, whereas altering the String.prototype is by far the slowest in terms of performance.

// 10,889,187 operations/sec
function capitalizeFirstLetter(string) {
 return string[0].toUpperCase() + string.slice(1);
}
// 10,875,535 operations/sec
function capitalizeFirstLetter(string) {
 return string.charAt(0).toUpperCase() + string.slice(1);
}
// 4,632,536 operations/sec
function capitalizeFirstLetter(string) {
 return string.replace(/^./, string[0].toUpperCase());
}
// 1,977,828 operations/sec
String.prototype.capitalizeFirstLetter = function() {
 return this.charAt(0).toUpperCase() + this.slice(1);
}

enter image description here

• Martijn Scheffer: i wonder why that last method is so slow, do you attach the function to the prototype every iteration ? that would be unfair
• cdosborn: I created a jsbench.me and added a method here: jsbench.me/mamdq8nnz2/1

Answer 7

For another case I need it to capitalize the first letter and lowercase the rest. The following cases made me change this function:

//es5
function capitalize(string) {
 return string.charAt(0).toUpperCase() + string.slice(1).toLowerCase();
}
capitalize("alfredo") // => "Alfredo"
capitalize("Alejandro")// => "Alejandro
capitalize("ALBERTO") // => "Alberto"
capitalize("ArMaNdO") // => "Armando"
// es6 using destructuring 
const capitalize = ([first,...rest]) => first.toUpperCase() + rest.join('').toLowerCase();

Answer 8

If you're already (or considering) using Lodash, the solution is easy:

_.upperFirst('fred');
// => 'Fred'
_.upperFirst('FRED');
// => 'FRED'
_.capitalize('fred') //=> 'Fred'

See their documentation: https://lodash.com/docs#capitalize

_.camelCase('Foo Bar'); //=> 'fooBar'

https://lodash.com/docs/4.15.0#camelCase

_.lowerFirst('Fred');
// => 'fred'
_.lowerFirst('FRED');
// => 'fRED'
_.snakeCase('Foo Bar');
// => 'foo_bar'

Vanilla JavaScript for first upper case:

function upperCaseFirst(str){
 return str.charAt(0).toUpperCase() + str.substring(1);
}

• tinystone: if chances are multiple words, try startCase. eg. _.startCase('fred') //=> 'Fred' _.startCase('fred doe') //=> 'Fred Doe'. note it removes hyphen eg. _.startCase('fred-doe') //=> 'Fred Doe'

Answer 9

This is the 2018 ECMAScript 6+ Solution:

const str = 'the Eiffel Tower';
const newStr = `${str[0].toUpperCase()}${str.slice(1)}`;
console.log('Original String:', str); // the Eiffel Tower
console.log('New String:', newStr); // The Eiffel Tower

Answer 10

There is a very simple way to implement it by replace. For ECMAScript 6:

'foo'.replace(/^./, str => str.toUpperCase())

Result:

'Foo'

• Code Maniac: Using /^[a-z]/i will be better than using . as the prior one will not try to replace any character other than alphabets
• msdos: @CodeManiac there are so many languages and letters except [a-z]
• Robin Métral: This is nice to avoid having to declare a string variable (that most other answers assume there is). For example: const date = new Date("2024年08月12日").toLocaleDateString("fr-FR", { weekday: "long", year: "numeric", month: "long", day: "numeric" }).replace(/^./, str => str.toUpperCase());. Using the string concatenation solution would require putting the locale date string in a variable first (or worse, repeating the full date method).

Answer 11

CSS only

If the transformation is needed only for displaying on a web page:

p::first-letter {
 text-transform: uppercase;
}

• Despite being called "::first-letter", it applies to the first character, i.e. in case of string %a, this selector would apply to % and as such a would not be capitalized.
• In IE9+ or IE5.5+ it's supported in legacy notation with only one colon (:first-letter).

ES2015 one-liner

const capitalizeFirstChar = str => str.charAt(0).toUpperCase() + str.substring(1);

Remarks

• In the benchmark I performed, there was no significant difference between string.charAt(0) and string[0]. Note however, that string[0] would be undefined for an empty string, so the function would have to be rewritten to use "string && string[0]", which is way too verbose, compared to the alternative.
• string.substring(1) is faster than string.slice(1).

Benchmark between substring() and slice()

The difference is rather minuscule nowadays (run the test yourself):

• 21,580,613.15 ops/s ±1.6% for substring(),
• 21,096,394.34 ops/s ±1.8% (2.24% slower) for slice().

Solutions' comparison

• Sterling Bourne: You actually don't want to use the plus sign (+) as a concatenation method in ES6. You'll want to use template literals: eslint.org/docs/rules/prefer-template
• Zachiah: @SterlingBourne why are you quoting an eslint rule like it should be followed by everyone?

Answer 12

Capitalize the first letter of all words in a string:

function ucFirstAllWords( str )
{
 var pieces = str.split(" ");
 for ( var i = 0; i < pieces.length; i++ )
 {
 var j = pieces[i].charAt(0).toUpperCase();
 pieces[i] = j + pieces[i].substr(1);
 }
 return pieces.join(" ");
}

• JimmyPena: Re-read question: I want to capitalize the first character of a string, but not change the case of any of the other letters.
• Malovich: I know I did. I'd add one thing, in case the entire string starts capitalized: pieces[i] = j + pieces[i].substr(1).toLowerCase()
• Luke Channings: Another solution to this case: function capitaliseFirstLetters(s) { return s.split(" ").map(function(w) { return w.charAt(0).toUpperCase() + w.substr(1) }).join(" ") } Can be a nice one-liner if it's not put into a function.
• Magico: Would be better to first lowercase the whole string
• OverCoder: Other than this function not answering the question, it's actually also overcomplicated. s => s.split(' ').map(x => x[0].toUpperCase() + x.slice(1)).join(' ')

Answer 13

It's always better to handle these kinds of stuff using CSS first, in general, if you can solve something using CSS, go for that first, then try JavaScript to solve your problems, so in this case try using :first-letter in CSS and apply text-transform:capitalize;

So try creating a class for that, so you can use it globally, for example: .first-letter-uppercase and add something like below in your CSS:

.first-letter-uppercase:first-letter {
 text-transform:capitalize;
}

Also the alternative option is JavaScript, so the best gonna be something like this:

function capitalizeTxt(txt) {
 return txt.charAt(0).toUpperCase() + txt.slice(1); //or if you want lowercase the rest txt.slice(1).toLowerCase();
}

and call it like:

capitalizeTxt('this is a test'); // return 'This is a test'
capitalizeTxt('the Eiffel Tower'); // return 'The Eiffel Tower'
capitalizeTxt('/index.html'); // return '/index.html'
capitalizeTxt('alireza'); // return 'Alireza'
capitalizeTxt('dezfoolian'); // return 'Dezfoolian'

If you want to reuse it over and over, it's better attach it to javascript native String, so something like below:

String.prototype.capitalizeTxt = String.prototype.capitalizeTxt || function() {
 return this.charAt(0).toUpperCase() + this.slice(1);
}

and call it as below:

'this is a test'.capitalizeTxt(); // return 'This is a test'
'the Eiffel Tower'.capitalizeTxt(); // return 'The Eiffel Tower'
'/index.html'.capitalizeTxt(); // return '/index.html'
'alireza'.capitalizeTxt(); // return 'Alireza'

Answer 14

String.prototype.capitalize = function(allWords) {
 return (allWords) ? // If all words
 this.split(' ').map(word => word.capitalize()).join(' ') : // Break down the phrase to words and then recursive
 // calls until capitalizing all words
 this.charAt(0).toUpperCase() + this.slice(1); // If allWords is undefined, capitalize only the first word,
 // meaning the first character of the whole string
}

And then:

 "capitalize just the first word".capitalize(); ==> "Capitalize just the first word"
 "capitalize all words".capitalize(true); ==> "Capitalize All Words"

Update November 2016 (ES6), just for fun:

const capitalize = (string = '') => [...string].map( // Convert to array with each item is a char of
 // string by using spread operator (...)
 (char, index) => index ? char : char.toUpperCase() // Index true means not equal 0, so (!index) is
 // the first character which is capitalized by
 // the `toUpperCase()` method
 ).join('') // Return back to string

then capitalize("hello") // Hello

• dudewad: I think this is a poor solution for 2 reasons: Modifying the prototype of a primitive is a bad idea. If the spec changes and they decide to pick 'capitalize' as a new proto property name, you're breaking core language functionality. Also, The method name chosen is poor. At first glance, I would think this will capitalize the entire string. Using a more descriptive name such as PHP's ucFirst or something similar might be a better idea.
• Dan Dascalescu: The other ES6 answer is simpler: const capitalize = ([first,...rest]) => first.toUpperCase() + rest.join('').toLowerCase();.
• Someone Special: @dudewad in css, capitalizing of first letter of a word is call 'capitalize', and if you want to capitalize all characters u use 'uppercase', hence it's not really bad choice.

Answer 15

SHORTEST 3 solutions, 1 and 2 handle cases when s string is "", null and undefined:

 s&&s[0].toUpperCase()+s.slice(1) // 32 char
 s&&s.replace(/./,s[0].toUpperCase()) // 36 char - using regexp
'foo'.replace(/./,x=>x.toUpperCase()) // 31 char - direct on string, ES6

let s='foo bar';
console.log( s&&s[0].toUpperCase()+s.slice(1) );
console.log( s&&s.replace(/./,s[0].toUpperCase()) );
console.log( 'foo bar'.replace(/./,x=>x.toUpperCase()) );

Answer 16

We could get the first character with one of my favorite RegExp, looks like a cute smiley: /^./

String.prototype.capitalize = function () {
 return this.replace(/^./, function (match) {
 return match.toUpperCase();
 });
};

And for all coffee-junkies:

String::capitalize = ->
 @replace /^./, (match) ->
 match.toUpperCase()

...and for all guys who think that there's a better way of doing this, without extending native prototypes:

var capitalize = function (input) {
 return input.replace(/^./, function (match) {
 return match.toUpperCase();
 });
};

• stwilz: Dear lordy there's a million answers to this question! Your solution looks even nicer in es6. 'Answer'.replace(/^./, v => v.toLowerCase())
• Peter Mortensen: What are you referring to by "coffee"? "CoffeeScript"?

Answer 17

Here is a function called ucfirst()(short for "upper case first letter"):

function ucfirst(str) {
 var firstLetter = str.substr(0, 1);
 return firstLetter.toUpperCase() + str.substr(1);
}

You can capitalise a string by calling ucfirst("some string") -- for example,

ucfirst("this is a test") --> "This is a test"

It works by splitting the string into two pieces. On the first line it pulls out firstLetter and then on the second line it capitalises firstLetter by calling firstLetter.toUpperCase() and joins it with the rest of the string, which is found by calling str.substr(1).

You might think this would fail for an empty string, and indeed in a language like C you would have to cater for this. However in JavaScript, when you take a substring of an empty string, you just get an empty string back.

• Dan Dascalescu: @999: where does it say that substr() is deprecated? It's not, even now, three years later, let alone back in 2009 when you made this comment.
• Peter Rust: substr() may not be marked as deprecated by any popular ECMAScript implementation (I doubt it's not going to disappear anytime soon), but it's not part of the ECMAScript spec. The 3rd edition of the spec mentions it in the non-normative annex in order to "suggests uniform semantics for such properties without making the properties or their semantics part of this standard".
• Peter Rust: Having 3 methods that do the same thing (substring, substr and slice) is too many, IMO. I always use slice because it supports negative indexes, it doesn't have the confusing arg-swapping behavior and its API is similar to slice in other languages.

Answer 18

If you're ok with capitalizing the first letter of every word, and your usecase is in HTML, you can use the following CSS:

<style type="text/css">
 p.capitalize {text-transform:capitalize;}
</style>
<p class="capitalize">This is some text.</p>

This is from CSS text-transform Property (at W3Schools).

• Adam Hepton: @Simon It's not stated that the string is necessarily going to be output as part of a HTML document - CSS is only going to be of use if it is.
• Simon E.: Adam, true, but I'd guess that over 95% of the Javascript out there is used with HTML & CSS. Unfortunately, the "capitalize" statement actually capitalizes every word, so you'd still need JS to capitalize only the first letter of the string.
• Simon E.: Incorrect, Dinesh. He said the first character of the string.
• Dan Dascalescu: This answer, despite having a ridiculous number of upvotes, is just wrong, as it will capitalize the first letter of every word. @Ryan, you'll earn a Disciplined badge if you delete it. Please do so.
• Ali Gangji: It's now javascript: $('.capitalize').css('text-transform', 'capitalize')

Answer 19

If you use Underscore.js or Lodash, the underscore.string library provides string extensions, including capitalize:

_.capitalize(string) Converts first letter of the string to uppercase.

Example:

_.capitalize("foo bar") == "Foo bar"

• bardzusny: Since, version 3.0.0, Lo-Dash has this string method available by default. Just like described in this answer: _.capitalize("foo") === "Foo".
• Stepan Zakharov: Also there are usefull underscore.js function called humanize. It converts an underscored, camelized, or dasherized string into a humanized one. Also removes beginning and ending whitespace, and removes the postfix '_id'.
• Igor Loskutov: From version 4*, Lodash also lowercase() every other letter, be careful!

Answer 20

Use:

var str = "ruby java";
console.log(str.charAt(0).toUpperCase() + str.substring(1));

It will output "Ruby java" to the console.

Answer 21

If you are wanting to reformat all-caps text, you might want to modify the other examples as such:

function capitalize (text) {
 return text.charAt(0).toUpperCase() + text.slice(1).toLowerCase();
}

This will ensure that the following text is changed:

TEST => Test
This Is A TeST => This is a test

• monokrome: Probably worth noting that this will also convert things like acronyms to lowercase, so maybe not the best idea in most cases
• monokrome: btw, this will break uppercasing acronyms so be careful y'all <3

Answer 22

var capitalized = yourstring[0].toUpperCase() + yourstring.substr(1);

• Nimantha: Could you elaborate with an explanation of the code?

Answer 23

yourString.replace(/\w/, c => c.toUpperCase())

I found this arrow function easiest. Replace matches the first letter character (\w) of your string and converts it to uppercase. Nothing fancier is necessary.

• Christian Vincenzo Traina: This should be the accepted answer, instead it's almost the last since SO keeps awarding outdated questions. Btw, it's better using /./ for two reason: /\w/ will skip all the previous not letter characters (so @@abc will become @@Abc), and then it doesn't work with not-latin characters
• Șerban Ghiță: This is a good answer! There is a small caveat: \w Matches any alphanumeric character from the basic Latin alphabet, including the underscore. so replacing a word like _boss will yield _boss (from developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/…)
• InSync: @ȘerbanGhiță The same would apply to 1boss. If matching an underscore is not the desired behaviour, use [A-Za-z-0-9] or [^\W_].

Answer 24

function capitalize(s) {
 // returns the first letter capitalized + the string from index 1 and out aka. the rest of the string
 return s[0].toUpperCase() + s.substr(1);
}
// examples
capitalize('this is a test');
=> 'This is a test'
capitalize('the Eiffel Tower');
=> 'The Eiffel Tower'
capitalize('/index.html');
=> '/index.html'

Answer 25

String.prototype.capitalize = function(){
 return this.replace(/(^|\s)([a-z])/g, 
 function(m, p1, p2) {
 return p1 + p2.toUpperCase();
 });
};

Usage:

capitalizedString = someString.capitalize();

This is a text string => This Is A Text String

• tomdemuyt: +1, this is what I was really looking for. There is a minor bug though, it ought to be return.this.toLocaleLowerCase().replace( ...
• Benubird: +1, I found this page looking for a javascript version of phps ucfirst, which I suspect is how most people find it.
• Travis Webb: @DanDascalescu I found this useful, so +1 utilitarianism, and -1 anal-retentiveness. He included an example, so its function is clear.
• IGRACH: String.prototype.capitalize = function(){ return this.replace( /(^|\s)[a-z]/g , function(m){ return m.toUpperCase(); }); }; I refactor your code a bit, you need only a first match.
• Przemek: Firstly, it does something else than OP asked for, secondly regex is an inefficient overkill in this case, lastly don't modify prototypes of something you don't own

Answer 26

A Solution That Works For All Unicode Characters

Over a hundred different answers for this question, and yet none of them raise the important issue that none of the solutions listed will work with Asian characters, emoji's, and other high Unicode-point-value characters in many browsers. Here is a solution that will:

const consistantCapitalizeFirstLetter = "\uD852\uDF62".length === 1 ?
 function(S) {
 "use-strict"; // Hooray! The browser uses UTF-32!
 return S.charAt(0).toUpperCase() + S.substring(1);
 } : function(S) {
 "use-strict";
 // The browser is using UCS16 to store UTF-16
 var code = S.charCodeAt(0)|0;
 return (
 code >= 0xD800 && code <= 0xDBFF ? // Detect surrogate pair
 S.slice(0,2).toUpperCase() + S.substring(2) :
 S.charAt(0).toUpperCase() + S.substring(1)
 );
 };
const prettyCapitalizeFirstLetter = "\uD852\uDF62".length === 1 ?
 function(S) {
 "use-strict"; // Hooray! The browser uses UTF-32!
 return S.charAt(0).toLocaleUpperCase() + S.substring(1);
 } : function(S) {
 "use-strict";
 // The browser is using UCS16 to store UTF-16
 var code = S.charCodeAt(0)|0;
 return (
 code >= 0xD800 && code <= 0xDBFF ? // Detect surrogate pair
 S.slice(0,2).toLocaleUpperCase() + S.substring(2) :
 S.charAt(0).toLocaleUpperCase() + S.substring(1)
 );
 };

Do note that the above solution tries to account for UTF-32. However, the specification officially states that browsers are required to do everything in UTF-16 mapped into UCS2. Nevertheless, if we all come together, do our part, and start preparing for UTF32, then there is a chance that the TC39 may allow browsers to start using UTF-32 (like how Python uses 24-bits for each character of the string). This must seem silly to an English speaker: no one who uses only latin-1 has ever had to deal with Mojibake because Latin-I is supported by all character encodings. But, users in other countries (such as China, Japan, Indonesia, etc.) are not so fortunate. They constantly struggle with encoding problems not just from the webpage, but also from the JavaScript: many Chinese/Japanese characters are treated as two letters by JavaScript and thus may be broken apart in the middle, resulting in � and � (two question-marks that make no sense to the end user). If we could start getting ready for UTF-32, then the TC39 might just allow browsers do what Python did many years ago which had made Python very popular for working with high Unicode characters: using UTF-32.

consistantCapitalizeFirstLetter works correctly in Internet Explorer 3+ (when the const is changed to var). prettyCapitalizeFirstLetter requires Internet Explorer 5.5+ (see the top of page 250 of this document). However, these fact are more of just jokes because it is very likely that the rest of the code on your webpage will not even work in Internet Explorer 8 - because of all the DOM and JScript bugs and lack of features in these older browsers. Further, no one uses Internet Explorer 3 or Internet Explorer 5.5 any more.

• Semicolon: Glad to see an answer that brings up this concern. However, I don’t believe there are any browsers where String.fromCodePoint(65536).length === 1 will be true. That ES strings expose their UTF16ishness isn’t implementation-specific behavior — it’s a well-defined part of the spec, and it can’t be fixed due to backwards compat.
• Semicolon: Re: the new final notes, WHATWG and co have landed on UTF-8 as the sole ‘correct’ encoding for all text interchange on the platform. This isn’t gonna change (and it’s a good thing). The ES issue is distinct from that, though — it’s about ES having a string abstraction where the code units of the internal ‘utf-16 + lone surrogates’ encoding (it’s neither UTF-16 nor UCS2 quite) ‘break through’ when using indexed address, String.prototype.length, etc. (1/2)
• Semicolon: The body responsible for ES is TC39 rather than W3C (or WHATWG, etc), and they cannot change the existing functionality because it would break the web. Instead, they can introduce new functionality that behaves correctly. They already have begun doing this — the 'u' flag on RegExp, String.prototype.codePointAt, and String.prototype[@@iterator] provide safer alternatives to the old APIs. (2/2)
• dsl101: Wow—almost 5 years old and lots of edits. It looks really useful, but this code has clearly never been run. S or string?
• Kevin B: While you're possibly correct that no other answers (at the time of your posting) dealt with these characters correctly, the question also didn't ask for this.

Answer 27

var str = "test string";
str = str.substring(0,1).toUpperCase() + str.substring(1);

Answer 28

You can also use a simple CSS transform:

text-transform: capitalize;

div.text-capitalize {
 text-transform: capitalize;
}

<h2>text-transform: capitalize:</h2>
<div class="text-capitalize">Lorem ipsum dolor sit amet, consectetur adipiscing elit.</div>

• stackoverflow: this will uppercase all words in a string
• Deen John: no, it only capitalize ist letter of each word in a sentence w3schools.com/cssref/tryit.asp?filename=trycss_text-transform
• Deen John: i specifically mentioned that besides javascript you can use css too...not everyone is probably looking for an interview question answer.
• Sean: This duplicates other prior answers.

Answer 29

Check out this solution:

var stringVal = 'master';
stringVal.replace(/^./, stringVal[0].toUpperCase()); // Returns Master

• Alfredo Delgado: Save some keystrokes ;) stringVal.replace(/^./, stringVal[0].toUpperCase());
• Przemek: Regex shouldn't be used where not necessary. It's greatly inefficient and it doesn't make code any more concise either. Moreover, stringVal[0] would be undefined for empty stringVal, and as such attempt to access property .toUpperCase() would throw an error.

Answer 30

yourString.replace(/^[a-z]/, function(m){ return m.toUpperCase() });

EDIT: Regexp is overkill for this, prefer the simpler : str.charAt(0).toUpperCase() + str.substring(1)

• Robin van Baalen: Even though this has quite some votes, this is by far the slowest solution posted here. I've put together a little speedtest with the most popular answers from this post, here: forwebonly.com/…
• Simon: Regexp is overkill for this, prefer the simpler : str.charAt(0).toUpperCase() + str.slice(1)
• Przemek: Often times, if you want to solve your problem with regex, you end up with two problems.