react js interview questions

process is more standardized, the amount of manual encoding is reduced, and the encoding efficiency is improved. At the same time, when data is updated, sometimes the component is not required, but it also needs to be re-drawn, which affects the efficiency. Generally, they are used only when building complex projects with multiple interactions and data streams. What are the disadvantages of redux? The data required by a component must be transmitted by the parent component, but cannot be dire

Js interview questions-inheritance of js, js questions-js Js is a flexible language. There are often multiple ways to implement a function.

Several common js interview questions and js interview 1. About the number type conversion in "+" and "-" Var a = ''+ 3; // try to convert 3 to the string var B = 4; console. log (typeof a); console. log (a + B); console. log (a-B); // try to convert the string to numbervar

Read the originalTwo years ago, we released our first article on Node. JS interview FAQ and answer, the JavaScript and Node. JS Ecosystem has had a lot of updates and developments in the last two years, so it's time to update these interview questions and Answers.Disclaimer

available within the code block until the variable is declared with the Let command. This is syntactically called a "temporary Dead zone" (Temporal Dead Zone, abbreviated as TDZ). Let variables cannot be declared repeatedlyLet does not allow the same variable to be declared repeatedly within the same scope. otherwise error:Uncaught SyntaxError: Identifier ‘XXX‘ has already been declaredFor example:let a = 0;let a = ‘sss‘;// Uncaught SyntaxError: Identifier ‘a‘ has already been declaredSumm

This article mainly shares several JavaScript interview questions. I hope this article will help you to pass the interview smoothly. For more information, see the relevant coders. 1. What are the two methods for creating JavaScript objects? This is a very simple problem if you have used JavaScript. You have at least learned one way. However, based on my experien

/requests, and improve program performance Cache usage Steps (1) Use the data, first to the cache to view, and then remove the use (2) no data in the cache, calculate/request, and then cache the Data. Cache application: Fibonacci Recursive functions Fibonacci-cut Sequence Optimization "cache" Script> varCache= {}; function Fn4(m){ if(cache[m]){ returncache[m]; } if(m=== 1 ||M=== 2){cache[m]= 1; return 1;

Differences between undefined, null, and NaN in JS, as well as interview questions about object attribute assignment, undefinednan (1) In the following three cases, the return type of typeof is undefined. -- When the variable is not initialized -- When the variable is undefined -- When the function does not return a specific value (undefined is returned when the

、 Controller 非常薄，只起到路由的作用，而 View 非常厚，业务逻辑都部署在 View。所以，Backbone 索性取消了 Controller，只保留一个 Router（路由器）Mvp MVP 模式将 Controller 改名为 Presenter，同时改变了通信方向。 View ==> Presenter ==> Model Model ==> Presenter ==> View 1、 各部分之间的通信，都是双向的。 2、View 与 Model 不发生联系，都通过 Presenter 传递。 3、View 非常薄，不部署任何业务逻辑，称为"被动视图"（Passive View），即没有任何主动性，而 Presenter非常厚，所有逻辑都部署在那里。MVVMMVVM 模式将 Presenter 改名为 ViewModel，基本上与 MVP 模式完全一致。 唯一的区别是，它采用双向绑定（data-binding）：View的变动，自动反映在 ViewModel，反之亦然。Angular 和 Ember 都采用这种模式。

; } } } returnarr}//previous backward comparison, different push to new arrayArray.prototype.distinct2 =function () { vararr = This; vartemp = []; for(vari=0; i) { for(varj=i+1; j) { if(Arr[i] = = =Arr[j]) {J= ++i; }} temp.push (Arr[i])}returnTemp}//attributes that cannot be duplicated by using object property namesARRAY.PROTOTYPE.DISTINCT3 =function () { varobj = {}; vararr = This; vartemp = []; for(

Original reference Https://mp.weixin.qq.com/s/mCVL6qI33XeTg4YGIKt-JQ1. Event BrokerAdds an event to the parent element, using the event bubbling principle, to get child elements based on E.targetLet Parentbox = document.getElementById (' Parentbox ');Parentbox.addeventlistener (' click ', Function (e) {if (e.target e.target.nodename = = = ' LI ') {Let item = E.target;Console.log (item);}})2. Using closures in loopsvar arr = [1,2,3,4,5];for (var i=0; iSetTimeout (function () {Console.log (i)},10

Blog relocation, to bring you the inconvenience, please understand!http://www.suanliutudousi.com/2017/11/25/%e5%89%8d%e7%ab%af%e9%9d%a2%e8%af%95%e9%a2%98%ef%bc%8cjs%e9%a2%84%e5% a4%84%e7%90%86%e9%83%a8%e5%88%86%e5%b0%8f%e7%bb%93%e5%87%bd%e6%95%b0%e5%a3%b0%e6%98%8e%e6%8f%90%e5%8d%87%e5%92 %8c%e5%8f%98/Front-end interview questions, JS preprocessing section Summary

development. Differences: React depends on Virtual DOM, while Vue. js uses DOM templates. The Virtual DOM used by React performs a dirty check on the rendered results. Vue. js provides instructions and filters in the template to operate DOM conveniently and quickly. Vue Life Cycle

Web Front-end interview questions, web interview questionsWelcome to reprint, but please indicate the source: http://blog.csdn.net/sysuzjz/article/details/44562467 The following questions come from the questions I have asked when applying for an application from various comp

Web Front-end interview questions, web interview questions I 'd like to share with you some of my recent interview questions. 1.Understanding and understanding of WEB standards and W3C Tag closure, lower-case tags, non-chaotic nes

variables, inheritance, operations, and functions. Less can be run on the client (ie 6+, Webkit, Firefox) or on the server (with node. js).Why use them? The structure is clear and easy to expand. It is easy to block browser private syntax differences. This needless to say, the package of browser syntax differences in the repetition of processing, reduce meaningless mechanical labor. Multiple inheritance can be easily implemented.

above are the JavaScript interview questions prepared for you. Have you done well? I hope you can check for missing questions before the interview and pass the examination smoothly. Articles you may be interested in: Use js to preview uploaded images (TX

the greatest significance to play out, "lean once run everywhere" 9. Data security Prior to 0.14, only DEV-PC and assert were supported, and local file patch loading was supported from the 0.14.0 realease version, with the latest version 0.15.1. Because if you want to dynamic capabilities, JS must be on the network side issued, JS itself is clear (even if

Android Interview Questions and answers (2), android Questions and answers1. Activity-related. Launchmode, OnSaveInstnceState, and lifecycle. Four default launchmodes and OnNewIntent callbacks. OnNewIntent-> OnRestart-> OnStart-> onResume OnActivity-> OnResume. OnNewIntent, OnActivityResult? OnNewIntent launchmode with singletask or singleInstance. But if set the

calling, apply, bind, and so on ). The second is to call the object method and output John Doe. 25. Give you a DOM element, create a function that can access all the child elements of the element, and pass each child element to the specified callback function. The function accepts two parameters: DOM The specified callback function. The original article uses Depth-First-Search to provide an implementation: function Traverse(p_element,p_callback) { p_callback(p_element); var list = p_elem