filter(function(item,index,array){}):对数组中的每一项运行给定函数,返回该函数调用结果值为true的项组成新的数组,原数组不变 varnumbers = [1,2,3,4,5,4,3,2,1];varfilterResult = numbers.filter(function(item, index, array) {return(item >3); })console.log(filterResult);//[4, 5, 4],...
I find -1 only marginally more readable than length — 1, and while it is possible to approximate negative array indices in Javascript with ES6 Proxy or Array.slice(-1)[0], both come with significant performance implications for what should otherwise constitute simple random access. 我发现-1可...
Find First and Last Position of Element in Sorted Array 2019-11-04 12:18 − Given an array of integers nums sorted in non-decreasing order, find the starting and ending position of a given target value. If target is not found ... CNoodle 0 522 ...
5.2:构造函数方法Array.from()转成数组 let arr2 = Array.from(arrayLike);//[ 'a', 'b','c'] 5.3:find()方法找出第一个符合条件的数组成员,若无则返回undefined var target = array.find((item, index) => item.index === 2) 5.4:findIndex()找出第一个符合条件的数组成员位置,没有返回 -1 5...
findIndex():与上面方法用法一样,不同的地方是查找的是第一个下标 返回:查找到的第一个值的下标,查找不到则返回-1,原数组不变。 var numbers = [4, 9, 16, 25, 29];var first = numbers.findIndex(myFunction);//返回3,原数组不变function myFunction(value,...
那么在ES6当中,查找一个符合要求的元素将变得特别简单。 我们可以使用find()函数来查找数组中符合要求的元素。该方法接收一个函数,函数的参数分别对应着 item,index,array arr.find((item, index, arr) => { if(item == "Jerry"){ return true;
function push(array, ...items) { array.push(...items); } function add(x, y) { return x + y; } const numbers = [4, 38]; add(...numbers) // 42 可以将某些数据结构转为数组 [...document.querySelectorAll('div')] 能够更简单实现数组复制 ...
const numbers = Array.of(1, 2, 3, 4, 5); 11.2 Array.from() 从类似数组或可迭代对象创建数组,提高数据的转换效率。 const arrayLike = { 0: 'a', 1: 'b', length: 2 }; const newArray = Array.from(arrayLike); 11.3 Array find() ...
Array.from() Array.isArray() Array.of() 三十一个原型 api: Array.prototype.concat() Array.prototype.copyWithin() Array.prototype.entries() Array.prototype.every() Array.prototype.fill() Array.prototype.filter() Array.prototype.find() Array.prototype.findIndex() Array.prototype.flat() Array.prot...
//Default function findArtist(name='lu', age='26') { ... } //Rest function f(x, ...y) { // y is an Array return x * y.length; } f(3, "hello", true) == 6 //Spread function f(x, y, z) { return x + y + z; } // Pass each elem of array as argument f(.....