Return integer from string in JavaScript

Question

So I have the following string

var str = "Ana has 27 apples";

Is there any function that can return only the number 27 from str as an integer ?

I have found an old thread here about something like this but it was about Java. However it got me into Regular Expressions.

And I went ahead and tried playing with this but nothing gone as I expected.. This is the last expression I tried before coming here:

 var str = "Ana has 27 apples";
 var regex = /([0-9])\d+/;
 var ret = str.match(regex);
 console.log(ret);

And it returns 27,2 but I don't want that 2 returned and I definitely do not want it as a string. The thing is that the number is not necessary 27 , its a given number and it can be any integer.

So can it be done with Regular Expressions or is there another ("better") way of doing it without supplimentary lines of code?

• Dave Newton: If you want to extract a string from a string, and convert it to a numeric value, you have to first extract it, then convert it--there's no way around that. The functionality can be wrapped up in a function so the mainline code doesn't have to think about it. Right now you're capturing two chunks of integers, but I don't know why you'd do that.
• ADyson: You're not getting a string, you're getting an array containing two values. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… says: "If the string matches the expression, it will return an Array containing the entire matched string as the first element, followed by any results captured in parentheses. If there were no matches, null is returned." /\d+/g will match multiple sets of numbers in the string and return the results, again in an array - see jsfiddle.net/bqf8cvt7/4 . You can convert each one using parseInt if required.

Answer 1

And it returns 27,2 but I don't want that 2 returned

See the documentation for match:

it will return an Array containing the entire matched string as the first element, followed by any results captured in parentheses

So the 27 is the whole match and the 2 is from the capture group [0-9].

You probably want /(\d+)/ instead (and then to extract the match from the array with ret[1])

I definitely do not want it as a string.

That's what parseInt, parseFloat and Unary plus + are for.

Answer 2

You can use parseInt in order to convert numeric string to number;

const str = "Ana has 27 apples";
const num = str.match(/\d+/)[0];
console.log(parseInt(num, 10))

Answer 3

Here you go:

match(/\d+/)[0] regex will help you to get number as string and then use parseInt() to get an integer.

Check below working example:

var str = "Ana has 27 apples";
var num = str.match(/\d+/)[0];
console.log(parseInt(num));

Answer 4

A different way to do it from what was provided by the other answers is to just remove all non numeric characters from the string, then what you are left with will be anything numeric.

function numericOnly(str) {
 return parseInt(str.replace(/\D+/g,''));
}

Note that this is only useful if you know there is only one number in the string. some example results:

console.log(numericOnly('Ana has 27 apples')); // 27
console.log(numericOnly('Ana has 27 apples and 42 oranges')); //2742
console.log(numericOnly('Ana has no apples')); // NaN

Answer 5

Add g on your REGEXP for a global match

var regex = /([0-9])\d+/g;

Hope this helps :>

var str = "Ana has 27 apples";
var regex = /([0-9])\d+/g;
var ret = str.match(regex);
console.log(ret)

Answer 6

Just modify your code like below

You will get 27 only

var str = "Ana has 27 apples";
 var regex = /\d+/;
 var ret = str.match(regex);
 console.log(ret);

Answer 7

You can just do /(\d+)/g which will return all integer groupings.

https://regexfiddler.com/e/hj7dmrxfba81/extract-integers