Here you can find the source of sum()
/* Sum all elements of an array. * Use of reduce with ES6 syntax */ Array.prototype.sum = function(){ return this.reduce((acc,x) => acc + x); }
Array.prototype.sum = function() { if (this.length === 0) { return 0; } else if (this.length === 1) { return parseInt(this[0], 10); } else { return this.reduce(function(x, y) { return x + y; }); ...
Array.prototype.sum = function(){ for(var i=0,sum=0;i<this.length;i++) { var val = Number(this[i]); if (!isNaN(val)) { sum += val; return sum; }; ...
Array.prototype.sum = function() { var result = 0; for (var i = 0; i < this.length; i++) result += this[i]; return result;
Array.prototype.sum = function(){ var sum = 0; for (var i of this){ sum += i; return sum;
Array.prototype.sum = function() { var sum = 0; for (var i = 0; i < this.length; i++) { if (!isNaN(Number(this[i]))) { sum += Number(this[i]); return sum; }; ...
Array.prototype.sum = function() { return this.isEmpty() ? 0 : this.reduce( (a, b) => { return a + b} ); };
Array.prototype.sum = function() { for ( var a = 0, c = this.length, b = 0; a < c; b += this[a++]) { return b };
Array.prototype.sum = function(array) { return this.reduce(function(a,b) { return a + b })
Array.prototype.sum = function(begin, end) { var total = 0; for (var i = begin >> 0 || 0, len = end + 1 >> 0 || this.length >> 0; i < len; i++) { total += +this[i] || 0; return total; };