Sum values from an Array in JavaScript

I have defined a JavaScript variables called myData which is a new Array like this:

var myData = new Array(['2013-01-22', 0], ['2013-01-29', 0], ['2013-02-05', 0],
             ['2013-02-12', 0], ['2013-02-19', 0], ['2013-02-26', 0], 
             ['2013-03-05', 0], ['2013-03-12', 0], ['2013-03-19', 0], 
             ['2013-03-26', 0], ['2013-04-02', 21], ['2013-04-09', 2]);

I am wondering if it is possible to sum the number values found in the array (ex. 0+0+21+2+0 and so on) and have probably a variable with the result that I can use outside of the script tag because I have 7 of this kind of arrays corresponding for each of the day in the week. I want to make a comparison afterwards based on that. That is the most preferred method for this kind of actions if is possible?

Answers


Try the following

var myData = [['2013-01-22', 0], ['2013-01-29', 1], ['2013-02-05', 21]];

var myTotal = 0;  // Variable to hold your total

for(var i = 0, len = myData.length; i < len; i++) {
    myTotal += myData[i][1];  // Iterate over your first array and then grab the second element add the values up
}

document.write(myTotal); // 22 in this instance

You could use the Array.reduce method:

const myData = [
  ['2013-01-22', 0], ['2013-01-29', 0], ['2013-02-05', 0],
  ['2013-02-12', 0], ['2013-02-19', 0], ['2013-02-26', 0], 
  ['2013-03-05', 0], ['2013-03-12', 0], ['2013-03-19', 0], 
  ['2013-03-26', 0], ['2013-04-02', 21], ['2013-04-09', 2]
];
const sum = myData
  .map( v => v[1] )                                
  .reduce( (sum, current) => sum + current, 0 );
  
console.log(sum);

I think the simplest way might be:

values.reduce(function(a, b){return a+b;})

I would use reduce

var myData = new Array(['2013-01-22', 0], ['2013-01-29', 0], ['2013-02-05', 0], ['2013-02-12', 0], ['2013-02-19', 0], ['2013-02-26', 0], ['2013-03-05', 0], ['2013-03-12', 0], ['2013-03-19', 0], ['2013-03-26', 0], ['2013-04-02', 21], ['2013-04-09', 2]);

var sum = myData.reduce(function(a, b) {
    return a + b[1];
}, 0);

$("#result").text(sum);

Available on jsfiddle


Creating a sum method would work nicely, e.g. you could add the sum function to Array

Array.prototype.sum = function(selector) {
    if (typeof selector !== 'function') {
        selector = function(item) {
            return item;
        }
    }
    var sum = 0;
    for (var i = 0; i < this.length; i++) {
        sum += parseFloat(selector(this[i]));
    }
    return sum;
};

then you could do

> [1,2,3].sum()
6

and in your case

> myData.sum(function(item) { return item[1]; });
23

Edit: Extending the builtins can be frowned upon because if everyone did it we would get things unexpectedly overriding each other (namespace collisions). you could add the sum function to some module and accept an array as an argument if you like. that could mean changing the signature to myModule.sum = function(arr, selector) { then this would become arr


Or in ES6

values.reduce((a, b) => a + b),

example:

[1,2,3].reduce((a, b)=>a+b) // return 6

If you want to discard the array at the same time as summing, you could do (say, stack is the array):

var stack = [1,2,3],
    sum = 0;
while(stack.length > 0) { sum += stack.pop() };

You can use the native map method for Arrays. map Method (Array) (JavaScript)

var myData = new Array(['2013-01-22', 0], ['2013-01-29', 0], ['2013-02-05', 0],
             ['2013-02-12', 0], ['2013-02-19', 0], ['2013-02-26', 0], 
             ['2013-03-05', 0], ['2013-03-12', 0], ['2013-03-19', 0], 
             ['2013-03-26', 0], ['2013-04-02', 21], ['2013-04-09', 2]);
var a = 0;
myData.map( function(aa){ a += aa[1];  return a; });

a is your result


The javascript built-in reduce for Arrays is not a standard, but you can use underscore.js:

var data = _.range(10);
var sum = _(data).reduce(function(memo, i) {return memo + i});

which becomes

var sumMyData = _(myData).reduce(function(memo, i) {return memo + i[1]}, 0);

for your case. Have a look at this fiddle also.


Old way (if you don't now the length of arguments/parameters)

 >> function sumla1(){

    result=0
    for(let i=0; i<arguments.length;i++){

        result+=arguments[i];

    }
    return result;
    }
    >> sumla1(45,67,88);
    >> 200

ES6 (destructuring of array)

>> function sumla2(...x){return x.reduce((a,b)=>a+b)}
>>
>> sumla2(5,5,6,7,8)
>>
>> 31
>>
>> var numbers = [4, 9, 16, 25];
>> sumla2(...numbers);
>> 54

Need Your Help

Beginning OpenGL 3.0+ Programming (again) in OS X, targeting multiple platforms

android ios macos graphics opengl-3

if this topic is a duplicate, I'm sorry, but I couldn't find the information I am asking anywhere.

configuring django to send email via the microsoft live smtp server

python django email smtp

I've signed up in Microsoft live SMTP server and created an email for my django app to send mail from my domain. But the problem is these configurations doesn't work and I can not send email from my