javascript - 请问数组里面的值如何进行相加

Question

比如；var array=[1,2,3,4],求和怎么 求的

Answer 1

var array=[1,2,3,4,5];
console.log(array.reduce((count,v) => count+v, 0))

reduce() 方法接收一个函数作为累加器（accumulator），数组中的每个值（从左到右）开始缩减，最终为一个值。
https://developer.mozilla.org...

兼容旧环境（Polyfill）

// Production steps of ECMA-262, Edition 5, 15.4.4.21
// Reference: http://es5.github.io/#x15.4.4.21
if (!Array.prototype.reduce) {
  Array.prototype.reduce = function(callback /*, initialValue*/) {
    'use strict';
    if (this == null) {
      throw new TypeError('Array.prototype.reduce called on null or undefined');
    }
    if (typeof callback !== 'function') {
      throw new TypeError(callback + ' is not a function');
    }
    var t = Object(this), len = t.length >>> 0, k = 0, value;
    if (arguments.length == 2) {
      value = arguments[1];
    } else {
      while (k < len && !(k in t)) {
        k++;
      }
      if (k >= len) {
        throw new TypeError('Reduce of empty array with no initial value');
      }
      value = t[k++];
    }
    for (; k < len; k++) {
      if (k in t) {
        value = callback(value, t[k], k, t);
      }
    }
    return value;
  };
}

Answer 2

var array=[1,2,3,4,5];
console.log(array.reduce((x ,y)=>{return x+y;}))