[javascript] Sum of values in an array using jQuery

I have an array containing some values and I want to get their sum. Here is the example:

var somearray = ["20","40","80","400"];

I want to sum these values using jQuery. In this example the result would be 540.

You can do it in this way.

var somearray = ["20","40","80","400"];

somearray = somearray.map(Number);

var total = somearray.reduce(function(a,b){  return a+b },0)

console.log(total);

To also handle floating point numbers:

• (Older) JavaScript:

  var arr = ["20.0","40.1","80.2","400.3"],
      n   = arr.length,
      sum = 0;
  while(n--)
     sum += parseFloat(arr[n]) || 0;
  

• ECMA 5.1/6:

  var arr = ["20.0","40.1","80.2","400.3"],
      sum = 0;
  arr.forEach(function(num){sum+=parseFloat(num) || 0;});
  

• ES6:

  var sum = ["20.0","40.1","80.2","400.3"].reduce((pv,cv)=>{
     return pv + (parseFloat(cv)||0);
  },0);
  

  ---

  The reduce() is available in older ECMAScript versions, the arrow function is what makes this ES6-specific.

  I'm passing in 0 as the first pv value, so I don't need parseFloat around it — it'll always hold the previous sum, which will always be numeric. Because the current value, cv, can be non-numeric (NaN), we use ||0 on it to skip that value in the array. This is terrific if you want to break up a sentence and get the sum of the numbers in it. Here's a more detailed example:

  let num_of_fruits = `
     This is a sentence where 1.25 values are oranges 
     and 2.5 values are apples. How many fruits are 
     there?
  `.split(/\s/g).reduce((p,c)=>p+(parseFloat(c)||0), 0); 
  
  // num_of_fruits == 3.75
  

  ---

• jQuery:

  var arr = ["20.0","40.1","80.2","400.3"],
      sum = 0;
  $.each(arr,function(){sum+=parseFloat(this) || 0;});
  

What the above gets you:

• ability to input any kind of value into the array; number or numeric string(123 or "123"), floating point string or number ("123.4" or 123.4), or even text (abc)
• only adds the valid numbers and/or numeric strings, neglecting any bare text (eg [1,'a','2'] sums to 3)

    var arr = ["20.0","40.1","80.2","400.3"],
    sum = 0;
$.each(arr,function(){sum+=parseFloat(this) || 0; });

Worked perfectly for what i needed. Thanks vol7ron

You can use reduce which works in all browser except IE8 and lower.

["20","40","80","400"].reduce(function(a, b) {
    return parseInt(a, 10) + parseInt(b, 10);
})

In http://bugs.jquery.com/ticket/1886 it becomes obvious that the jQuery devs have serious mental issues reg. functional programming inspired additions. Somehow it's good to have some fundamental things (like map) but not others (like reduce), unless it reduces jQuery's overall filesize. Go figure.

Helpfully, someone placed code to use the normal reduce function for jQuery arrays:

$.fn.reduce = [].reduce;

Now we can use a simple reduce function to create a summation:

//where X is a jQuery array
X.reduce(function(a,b){ return a + b; });
// (change "a" into parseFloat("a") if the first a is a string)

Lastly, as some older browsers hadn't yet implemented reduce, a polyfill can be taken from MDN (it's big but I guess it has the exact same behavior, which is desirable):

if ( 'function' !== typeof Array.prototype.reduce ) {
    Array.prototype.reduce = function( callback /*, initialValue*/ ) {
        'use strict';
        if ( null === this || 'undefined' === typeof this ) {
          throw new TypeError(
             'Array.prototype.reduce called on null or undefined' );
        }
        if ( 'function' !== typeof callback ) {
          throw new TypeError( callback + ' is not a function' );
        }
        var t = Object( this ), len = t.length >>> 0, k = 0, value;
        if ( arguments.length >= 2 ) {
          value = arguments[1];
        } else {
          while ( k < len && ! k in t ) k++; 
          if ( k >= len )
            throw new TypeError('Reduce of empty array with no initial value');
          value = t[ k++ ];
        }
        for ( ; k < len ; k++ ) {
          if ( k in t ) {
             value = callback( value, t[k], k, t );
          }
        }
        return value;
      };
    }

Another method, if eval is safe & fast :

eval(["10","20","30","40","50"].join("+"))

var total = 0;
$.each(someArray,function() {
    total += parseInt(this, 10);
});

If you want it to be a jquery method, you can do it like this :

$.sum = function(arr) {
    var r = 0;
    $.each(arr, function(i, v) {
        r += +v;
    });
    return r;
}

and call it like this :

var sum = $.sum(["20", "40", "80", "400"]);