Sum values from an Array in JavaScript

Question

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

var myData = new Array([\'2013-01-22\', 0], [\'         


        

Answer 1

Or in ES6

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

example:

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

Answer 2

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

Answer 3

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() };

Answer 4

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);

See MDN

Answer 5

I think the simplest way might be:

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

Answer 6

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.