How to convert a string of numbers to an array of numbers?

Question

I have below string -

var a = \"1,2,3,4\";

when I do -

var b = a.split(\',\');

I get b as

Answer 1

A more shorter solution: map and pass the arguments to Number:

var a = "1,2,3,4";
var b = a.split(',');
console.log(b);
var c = b.map(Number);
console.log(c);

Answer 2

+string will try to change the string to a number. Then use Array.map function to change every element.

"1,2,3,4".split(',').map(function(el){ return +el;});

Answer 3

Matt Zeunert's version with use arraw function (ES6)

const nums = a.split(',').map(x => parseInt(x, 10));

Answer 4

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 5

This is very simple.Such as:

["1", "2", "3", "4"].map(i=>Number(i))

you can run the demo.

let result = ["1", "2", "3", "4"].map(i=>Number(i));
console.log(result);

Answer 6

As a variant you can use combiantion _.map and _.ary methods from the lodash library. Whole transformation will be a more compact. Here is example from the official documentation:

_.map(['6', '8', '10'], _.ary(parseInt, 1));
// → [6, 8, 10]