How to find the sum of an array of numbers

Question

Given an array [1, 2, 3, 4], how can I find the sum of its elements? (In this case, the sum would be 10.)

I thought $.each might be useful,

Answer 1

Those are really great answers, but just in case if the numbers are in sequence like in the question ( 1,2,3,4) you can easily do that by applying the formula (n*(n+1))/2 where n is the last number

Answer 2

This is much easier

function sumArray(arr) {
    var total = 0;
    arr.forEach(function(element){
        total += element;
    })
    return total;
}

var sum = sumArray([1,2,3,4])

console.log(sum)

Answer 3

You can also use reduceRight.

[1,2,3,4,5,6].reduceRight(function(a,b){return a+b;})

which results output as 21.

Reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/ReduceRight

Answer 4

var totally = eval(arr.join('+'))

That way you can put all kinds of exotic things in the array.

var arr = ['(1/3)','Date.now()','foo','bar()',1,2,3,4]

I'm only half joking.

Answer 5

No need to initial value! Because if no initial value is passed, the callback function is not invoked on the first element of the list, and the first element is instead passed as the initial value. Very cOOl feature :)

[1, 2, 3, 4].reduce((a, x) => a + x) // 10
[1, 2, 3, 4].reduce((a, x) => a * x) // 24
[1, 2, 3, 4].reduce((a, x) => Math.max(a, x)) // 4
[1, 2, 3, 4].reduce((a, x) => Math.min(a, x)) // 1

Answer 6

Object.defineProperty(Object.prototype, 'sum', {
    enumerable:false,
    value:function() {
        var t=0;for(var i in this)
            if (!isNaN(this[i]))
                t+=this[i];
        return t;
    }
});

[20,25,27.1].sum()                 // 72.1
[10,"forty-two",23].sum()          // 33
[Math.PI,0,-1,1].sum()             // 3.141592653589793
[Math.PI,Math.E,-1000000000].sum() // -999999994.1401255

o = {a:1,b:31,c:"roffelz",someOtherProperty:21.52}
console.log(o.sum());              // 53.519999999999996