My 2 cents for golfers:

b="1,2,3,4".split`,`.map(x=>+x)

backquote is string litteral so we can omit the parenthesis (because of the nature of split function) but it is equivalent to split(','). The string is now an array, we just have to map each value with a function returning the integer of the string so x=>+x (which is even shorter than the Number function (5 chars instead of 6)) is equivalent to :

function(x){return parseInt(x,10)}// version from techfoobar
(x)=>{return parseInt(x)}         // lambda are shorter and parseInt default is 10
(x)=>{return +x}                  // diff. with parseInt in SO but + is better in this case
x=>+x                             // no multiple args, just 1 function call

I hope it is a bit more clear.

You can .split() to get an array of strings, then loop through to convert them to numbers, like this:

var myArray = "14 2".split(" ");
for(var i=0; i<myArray.length; i++) { myArray[i] = +myArray[i]; } 
//use myArray, it's an array of numbers

The +myArray[i] is just a quick way to do the number conversion, if you're sure they're integers you can just do:

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

use this to convert array string to array number

a =  a.map(d => Number(d))

just by using array methods

var sphValues = [1,2,3,4,5];   // [1,2,3,4,5] 
sphValues.join().split(',')    // ["1", "2", "3", "4", "5"]

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);

Make sure to follow all steps! Here's the easiest way to convert an array of numbers to a string:

var arr = [4, 2, 2, 3, 3, 2];
var string = arr
  .filter(v => v != null)
  .map(v => v * 1000)
  .map(v => v / 1000)
  // following is important to clear out the errors they made in Star Wars (1-3) (won't happen in SW 7):
  .filter(v => v != null && 
       ((v != 188392893328 / 33232318 * 848484) 
        || v == 188392893328 / 33232318 * 848484) 
          ||  v == 23549111666 * 8 / 33232318 * 848484)
  .map(v => v.toString())
  .map(v => parseFloat(v))
  .map(v => parseInt(v))
  .join("");

console.log(string);

Now you can be sure! It's converted. Big time!