How to convert all elements in an array to integer in JavaScript?

Question

I am getting an array after some manipulation. I need to convert all array values as integers.

My sample code

var result_string = 'a,b,c,d|1,2,3,4';
result = result_string.split("|");
alpha = result[0];
count = result[1];
// console.log(alpha);
// console.log(count);
count_array = count.split(",");

count_array now contains 1,2,3,4 but I need these value to be in integers.

I had used parseInt(count_array);, but it fails. JS considers each value in this array as string.

Answer 1

ECMAScript5 provides a map method for Arrays, applying a function to all elements of an array. Here is an example:

var a = ['1','2','3']
var result = a.map(function (x) { 
 return parseInt(x, 10); 
});
console.log(result);

See Array.prototype.map()

• German Latorre: For compatibility issues, please note that Array.map() method is not available in IE8 and below
• Muhammad Musavi: It will be better if you use arrow function like this a = a.map((x) =>parseInt(x)); Or even this one: a = a.map((x) => +x);
• Tom McDonough: @Mohammadlm71 I have had problems in IE using arrow functions
• Y4glory: @MohammadMusavi arrow functions do not work in IE11

Answer 2

You can do

var arrayOfNumbers = arrayOfStrings.map(Number);

• MDN Array.prototype.map

For older browsers which do not support Array.map, you can use Underscore

var arrayOfNumbers = _.map(arrayOfStrings, Number);

• Anh Tran: Very nice. If you use underscores (for old browsers which do not support Array.map), you can do var newArray = _.map(oldArray, Number);
• Ola: The underscore doesn't work for me, I'm using updated Chrome Version 80.0.3987.132, I'm getting _ is not defined
• Dror Bar: Very nice. How does this work? Usually map takes a function, like this: val => Number(val)

Answer 3

Number() can convert a string to a number like this:

var arr = ["1", "2", "3"];
arr = arr.map(Number);
console.log(arr); // [1, 2, 3]

• Tom Aranda: This is a correct answer, but it is substantially no different than another answer to this question that already has 47 upvotes. Furthermore, answers are much more helpful if they include an explanation of what the code is intended to do, and why that solves the problem without introducing others.
• chzwzrd: @TomAranda Oops, my bad...this was my first answer post, so I may have been a little too eager to put in my 2 cents. Should have read through all of the answers carefully before submitting my own. Thanks for the feedback! I will keep it in mind.
• CandleCoder: Nice answer! Keep it up

Answer 4

You need to loop through and parse/convert the elements in your array, like this:

var result_string = 'a,b,c,d|1,2,3,4',
 result = result_string.split("|"),
 alpha = result[0],
 count = result[1],
 count_array = count.split(",");
for(var i=0; i<count_array.length;i++) count_array[i] = +count_array[i];
//now count_array contains numbers

You can test it out here. If the +, is throwing, think of it as:

for(var i=0; i<count_array.length;i++) count_array[i] = parseInt(count_array[i], 10);

• Álvaro González: Actually, parseInt("8foo", 10) returns 8 while +"8foo" returns NaN. Your approach is actually more strict with invalid numbers, I like it.
• Ruben Martinez Jr.: I might also suggest using something like "74" >> 0, a bitwise shift right by zero. Does the job well, is strict, and much more efficient than the alternatives. The second-best option efficiency-wise is doing a "not not" operation: ~~"74"
• Kian: @RubenMartinezJr. It's not that strict because "Not a number" >> 0 == 0

Answer 5

Just loop the array and convert items:

for(var i=0, len=count_array.length; i<len; i++){
 count_array[i] = parseInt(count_array[i], 10);
}

Don't forget the second argument for parseInt.

Answer 6

The point against parseInt-approach:

There's no need to use lambdas and/or give radix parameter to parseInt, just use parseFloat or Number instead.

---

Reasons:

1. It's working:

   var src = "1,2,5,4,3";
   var ids = src.split(',').map(parseFloat); // [1, 2, 5, 4, 3]
   var obj = {1: ..., 3: ..., 4: ..., 7: ...};
   var keys= Object.keys(obj); // ["1", "3", "4", "7"]
   var ids = keys.map(parseFloat); // [1, 3, 4, 7]
   var arr = ["1", 5, "7", 11];
   var ints= arr.map(parseFloat); // [1, 5, 7, 11]
   ints[1] === "5" // false
   ints[1] === 5 // true
   ints[2] === "7" // false
   ints[2] === 7 // true
   

2. It's shorter.

3. It's a tiny bit quickier and takes advantage of cache, when parseInt-approach - doesn't:

    // execution time measure function
    // keep it simple, yeah?
   > var f = (function (arr, c, n, m) {
    var i,t,m,s=n();
    for(i=0;i++<c;)t=arr.map(m);
    return n()-s
    }).bind(null, "2,4,6,8,0,9,7,5,3,1".split(','), 1000000, Date.now);
   > f(Number) // first launch, just warming-up cache
   > 3971 // nice =)
   > f(Number)
   > 3964 // still the same
   > f(function(e){return+e})
   > 5132 // yup, just little bit slower
   > f(function(e){return+e})
   > 5112 // second run... and ok.
   > f(parseFloat)
   > 3727 // little bit quicker than .map(Number)
   > f(parseFloat)
   > 3737 // all ok
   > f(function(e){return parseInt(e,10)})
   > 21852 // awww, how adorable...
   > f(function(e){return parseInt(e)})
   > 22928 // maybe, without '10'?.. nope.
   > f(function(e){return parseInt(e)})
   > 22769 // second run... and nothing changes.
   > f(Number)
   > 3873 // and again
   > f(parseFloat)
   > 3583 // and again
   > f(function(e){return+e})
   > 4967 // and again
   > f(function(e){return parseInt(e,10)})
   > 21649 // dammit 'parseInt'! >_<
   

Notice: In Firefox parseInt works about 4 times faster, but still slower than others. In total: +e < Number < parseFloat < parseInt

Answer 7

If you want to convert an Array of digits to a single number just use:

Number(arrayOfDigits.join(''));

Example

const arrayOfDigits = [1,2,3,4,5];
const singleNumber = Number(arrayOfDigits.join(''));
console.log(singleNumber); //12345

Answer 8

var inp=readLine();//reading the input as one line string
var nums=inp.split(" ").map(Number);//making an array of numbers
console.log(nums);`

input : 1 9 0 65 5 7 output:[ 1, 9, 0, 65, 5, 7 ]

what if we dont use .map(Number)

code

var inp=readLine();//reading the input as one line string
var nums=inp.split(" ");//making an array of strings
console.log(nums);

input : 1 9 0 65 5 7 output:[ '1', '9', '0', '65', '5', '7']

Answer 9

const arrString = ["1","2","3","4","5"];
const arrInteger = arrString.map(x => Number.parseInt(x, 10));

Above one should be simple enough,

One tricky part is when you try to use point free function for map as below

const arrString = ["1","2","3","4","5"];
const arrInteger = arrString.map(Number.parseInt);

In this case, result will be [1, NaN, NaN, NaN, NaN] since function argument signature for map and parseInt differs

map expects - (value, index, array) where as parseInt expects - (value, radix)

Answer 10

const arrayNumbers = arrayStrings.split(",").map((element)=> parseInt(element));

Answer 11

How about this:

let x = [1,2,3,4,5]
let num = +x.join("")

Answer 12

Using jQuery, you can like the map() method like so;

 $.map(arr, function(val,i) { 
 return parseInt(val); 
 });

Answer 13

use "join()"

let digits =[1,2,3,4]
let number =digits.join("")
console.log(number)

the '("")'- is used to indicate the separator,if you use 'digits.join("a")', it will give : 1a2a3a4

Answer 14

To convert array of Integer to a Integer value you can use reduce() method of Javascript. Below is the example :

 const arrayOfDigits = [1, 2, 3, 4, 5];
 const int = arrayOfDigits.reduce((val, digit) => (val * 10) + digit, 0);
 console.log('Array to Integer : '+int); //12345
 console.log('Add to Integer : '+(int+1)); //123456

Answer 15

The simplest way to do this is to convert the array into string and then parse it as integer:

var result_string = 'a,b,c,d|1,2,3,4';
result = result_string.split("|");
alpha = result[0];
count = result[1];
console.log(alpha);
console.log(count);
count_array = parseInt(count.split(",").join(''));
console.log(count_array);