Creating an array of cumulative sum in javascript

Question

This is an example of what I need to do:

var myarray = [5, 10, 3, 2];

var result1 = myarray[0];
var result2 = myarray[1] + myarray[0];
var result3 = myarray         


        

Answer 1

A more generic (and efficient) solution:

Array.prototype.accumulate = function(fn) {
    var r = [this[0]];
    for (var i = 1; i < this.length; i++)
        r.push(fn(r[i - 1], this[i]));
    return r;
}

or

Array.prototype.accumulate = function(fn) {
    var r = [this[0]];
    this.reduce(function(a, b) {
        return r[r.length] = fn(a, b);
    });
    return r;
}

and then

r = [5, 10, 3, 2].accumulate(function(x, y) { return x + y })