We often want to check if an array includes a specific item. It's been common to do this with the Array.prototype.indexOf method, but now we have a simpler way: We can use the Array.prototype.includes method, which is available starting with ES2016.…

js & array remove one item ways // array remove one item ways let keys = [1,2,3,4,5,6,7]; let key = 3; // keys.remove(key); ??? let index = keys.indexOf(key); // keys = keys.splice(index, 1); // keys = keys.slice(index, index + 1); keys = keys.filter…

这是我在逛 Stack Overflow 时遇见的一个高分问题:Why is processing a sorted array faster than an unsorted array?,我觉得这是一个非常好的用来讲分支预测(Branch Prediction)的例子,分享给大家看看 一.问题引入 先看这个代码: #include <algorithm> #include <ctime> #include <iostream> #include <stdint…

一直以来,在前端开发时使用的基本都是ES5,以及少量的ES6.3月份换工作面试时,发现一些比较大的公司,对ES6比较重视,阿里的面试官直接问ES7和ES8,对于从未接触过人来说,完全是灾难.由此也显现出我的一个弊端,埋头苦干是没用的,还要着眼未来,紧盯发展趋势.近期在补习ES6.ES7和ES8. ES7仅仅新增了求幂运算符(**)和Array.prototype.includes()方法两项内容,大大降低了学习难度,也预示着ES标准进入了小步快跑.多次少量更新的发展阶段. 1.求幂运算符(**)…

if (!Array.prototype.includes) {   Array.prototype.includes = function(searchElement /*, fromIndex*/ ) {     'use strict';     var O = Object(this);     var len = parseInt(O.length) || 0;     if (len === 0) {       return false;     }     var n = par…

前言 我们在判断某一个字符是否存在于一个字符串中或者某一个值是否存在于一个数组中时,ES7之前我们需要使用indexOf,ES7引入了新的方法includes 语法 数组:Array.inexOf(searchElement, startIndex) 字符串:String.inexOf(searchElement, startIndex) 第一个参数searchElement是要检索的值 第二个参数是可选值,从何处开始进行检索,如果不规定此值,则默认从首字符开始检索 查看数组和字符串的原型链我们…

Iterating through/Parsing JSON Object via JavaScript 解答1 Your JSON object is incorrect because it has multiple properties with the same name. You should be returning an array of "student" objects. [ { "id": 456, "full_name":…

Remove Duplicates from Sorted Array Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length. Do not allocate extra space for another array, you must do this in place with constant memory.…

Search in Rotated Sorted Array Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). You are given a target value to search. If found in the array return its index, otherwise retu…

以下三个问题的典型的两个指针处理数组的问题,一个指针用于遍历,一个指针用于指向当前处理到位置 一:Remove Element Given an array and a value, remove all instances of that value in place and return the new length. The order of elements can be changed. It doesn't matter what you leave beyond the new l…