Summing Totals In JavaScript Array

Question

I have a dynamic JavaScript array that is being created on my page (none of these numbers will ever be the same, many variations), for example:

 myArray[ 1 ] = [295518, 2];
 myArray[ 2 ] = [123518, 123];
 myArray[ 3 ] = [295518, 43];
 myArray[ 4 ] = [295518, 65];
 myArray[ 5 ] = [234518, 3];
 myArray[ 6 ] = [567518, 56];

Explanation of this array:

                [id number, quantity]
 myArray[ 1 ] = [295518,    2];

I need to group all of the like id array elements together and sum their values.

 For instance: 295518 would add 2 + 43 + 65 = 110

Then I need it to update the id on the page with the value:

 $("#295518").text(110);

So what I am thinking is this, but I am not sure how to write it in JavaScript:

 [start JavaScript loop]
      [grab distinct ids]
           [start id loop]
                [grab all values based on id]
                [sum their qty values]
                [set the id element on the page with the sum value]
                     [example: $("#295518").text(110); ]
           [end id loop]
 [/end JavaScript loop]

why do i need to use proper terminology if you already know what i mean lol. — LargeTuna
– LargeTuna, Commented Feb 6, 2014 at 16:28
@LargeTuna So you at least sound like you might know what you're talking about. That's more important than you seem to think. — Anthony Grist
– Anthony Grist, Commented Feb 6, 2014 at 16:30
I get it. Again why is it important to seem like I know what I am talking about, results are all I need. I clearly seemed like i knew what i was talking about when i posted the post. — LargeTuna
– LargeTuna, Commented Feb 6, 2014 at 16:32

adiga · Accepted Answer · 2019-11-27 11:33:15Z

This should do the trick:

var myArray = [
  [295518, 2],
  [123518, 123],
  [295518, 43],
  [295518, 65],
  [234518, 3],
  [567518, 56]
]

var result = {};

for (var i in myArray) {
  var key = myArray[i][0];
  var value = myArray[i][1];
  if (result[key]) {
    result[key] += value;
  } else {
    result[key] = value;
  }
}

console.log(result);

Here's the same thing with jQuery :

var myArray = [];
myArray.push([295518, 2]);
myArray.push([123518, 123]);
myArray.push([295518, 43]);
myArray.push([295518, 65]);
myArray.push([234518, 3]);
myArray.push([567518, 56]);

var result = {};

$(myArray).each(function() {
  var key = this[0];
  var value = this[1];
  if (result[key]) {
    result[key] += value;
  } else {
    result[key] = value;
  }
});

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

Here's a working example...

André Dion · Accepted Answer · 2014-02-06 16:28:25Z

0

Assuming myArray always contains arrays with a length of 2, you could do the following:

var myArray = [
    [295518, 2],
    [123518, 123],
    [295518, 43],
    [295518, 65],
    [234518, 3],
    [567518, 56]
];
var allSums = {};

$.each(myArray, function( i, pair ) {
    if( allSums[pair[0]] ) {
        allSums[pair[0]] += pair[1];
    }
    else {
        allSums[pair[0]] = pair[1];
    }
});

DEMO

answered Feb 6, 2014 at 16:28

André Dion

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