Question

187

Sum of all elements in an array

rated 0 times [ 193] [ 6] / answers: 1 / hits: 25503 / 9 Years ago, sat, january 16, 2016, 12:00:00

I am a beginner in programming. I want to do the sum of all elements in an array. I made this but I can't see where are my mistakes?

function ArrayAdder(_array) {

    this.sum = 0;

    this.array = _array || [];

}



ArrayAdder.prototype.computeTotal = function () {

    this.sum = 0;

    this.array.forEach(function (value) {

        this.sum += value;

    });

    return this.sum;

};



var myArray = new ArrayAdder([1, 2, 3]);

console.log(myArray.computeTotal());

Answers

Only authorized users can answer the question. Please sign in first, or register a free account.

marcos

Add To Favorites

Follow

Total Points: 331

Total Questions: 106

Total Answers: 104

Location: Gabon

Member since Sat, Jul 25, 2020

4 Years ago

answered 9 Years ago trevionbronsonr · Accepted Answer

this inside the forEach callback refers to the global window object. To set the context of the callback, use the Array#forEach second argument to pass the context.

this.array.forEach(function (value) {

    this.sum += value;

}, this); // <-- `this` is bound to the `forEach` callback.

function ArrayAdder(_array) {

    this.sum = 0;

    this.array = _array || [];

}



ArrayAdder.prototype.computeTotal = function () {

    this.sum = 0;

    this.array.forEach(function (value) {

        this.sum += value;

    }, this);

    return this.sum;

};



var myArray = new ArrayAdder([1, 2, 3]);



console.log(myArray.computeTotal());

document.write(myArray.computeTotal()); // For Demo purpose

If you're looking for an alternative, you can use Array#reduce, here using with Arrow function

var sum = arr.reduce((x, y) => x + y);

// Note: If this doesn't work in your browser,

// check in the latest version of Chrome/Firefox



var arr = [1, 2, 3];

var sum = arr.reduce((x, y) => x + y);



document.write(sum);