reduce 函数很容易转换成 async function,但并行性却很难搞清楚。幸运的是,它很少破坏任何东西。 但在一些资源密集型或速度限制的情况下,了解函数的调用方式是至关重要的。
prototype.flat2 = function (n = 1) { const len = this.length let count = 0 let current = this if (!len || n === 0) { return current } // Confirm whether there are array items in current const hasArray = () => current.some((it) => Array.isArray(it)) // Expand one ...
let arr = [[0, 1], [2, 3], [4,[5,6,7]]] const newArr =function(arr){ returnarr.reduce((pre,cur)=>pre.concat(Array.isArray(cur)?newArr(cur):cur),[]) } console.log(newArr(arr));//[0, 1, 2, 3, 4, 5, 6, 7] (4)、对象里的属性求和 varresult = [ { subject:'...
let sum= arr.reduce(function(prev, cur, index, arr) { console.log(prev, cur, index);returnprev +cur; })//报错,"TypeError: Reduce of empty array with no initial value" 但是要是我们设置了初始值就不会报错,如下: //空数组,但设置 初始值 的情况let arr =[]; let sum= arr.reduce(functi...
PHParray_reduce()Function ❮ PHP Array Reference Example Send the values in an array to a user-defined function and return a string: <?php functionmyfunction($v1,$v2) { return$v1 ."-". $v2; } $a=array("Dog","Cat","Horse"); ...
The REDUCE function applies a LAMBDA function to each value in an array and returns the total value in the accumulator, reducing the array to an accumulated value.Syntax =REDUCE ([initial_value],array,lambda(accumulator, value))Arguments
Reduces an array to an accumulated value by applying a LAMBDA function to each value and returning the total value in the accumulator
const sum = arr.reduce(function(accumulator, currentValue, currentIndex, array){ console.log(accumulator, currentValue, currentIndex, array) return accumulator + currentValue }, 0) // 执行顺序 // 0 0 0 (5) [0, 1, 2, 3, 4] // 0 1 1 (5) [0, 1, 2, 3, 4] ...
[0,1,2,3,4].reduce(function(t,v,i,a){returnt+v;}); callback 被调用四次,每次调用的参数和返回值如下表: 03 reduce方法的应用 reduce() 的几个强大用法: 数组求和 代码语言:javascript 代码运行次数:0 运行 AI代码解释 vartotal=[0,1,2,3].reduce((acc,cur)=>{returnacc+cur},0);console....
用于执行每个数组元素的函数* @param initialValue 可选参数,传递给函数的初始值*/array.reduce(/*** @param total 必要参数,初始值或计算结束后的结果。* @param currentValue 必要参数,当前元素* @param currentIndex 可选参数,当前参数的下标* @param arr 可选...