reduce method javascript
// Reduce() method executes a callback function that is passed in // on each element of the array, resulting in single output value. const array1 = [1, 2, 3, 4]; const callback = (accumulator, currentValue) => accumulator + currentValue; // 1 + 2 + 3 + 4 console.log(array1.reduce(callback)); // expected output: 10 // 5 + 1 + 2 + 3 + 4 console.log(array1.reduce(callback, 5)); // expected output: 15 because the initial value is 5. // This is how Reduce works. // This is a myReduce method which takes a callback and an optional argument // of a default accumulator. If myReduce only receives one argument, then // myReduce will use the first element as the accumulator. Array.prototype.myReduce = function(callback, acc) { if (!acc) { acc = this.shift(); } this.forEach(function(element) { acc = callback(acc, element) }) return acc; }
