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1. Let's start with the conclusion key in Vue is the identification of DOM object;In list display, the default key is index;If the data is only used for display, there is no problem using index as the key;If you use index as the key, and subsequent operations will destroy the order, it will certainly bring efficiency problems. In serious cases ...

1, What is cross domain When a page or script under the domain name a.qq.com attempts to request resources under the domain name b.qq.com, it is a typical cross domain behavior. The definition of cross domain can be divided into two types: broad cross domain and narrow cross domain. (1) Generalized cross domain Generalized cross doma ...

In this section, we will learn how to get or set the width and height of elements through the methods provided in jQuery. The methods used to obtain and set the width and height in jQuery are as follows: methoddescribewidth()Sets or returns the width of the elementheight()Sets or returns the height of the elementinnerWidth()Returns the width ...

try{               // Exceptions may be thrown   throw }catch(){         // Catch exception }finally{           No matter whether an exception is thrown or caught, it will come here, except return. } In c, goto cannot cross functions, while setj ...

Mobile web effects Touch Event The mobile terminal browser has good compatibility. It does not need to consider the compatibility of previous JS. You can safely use the native JS writing effect, but the mobile terminal also has its own unique features. For example, touch (also known as touch event), Android and IOS have both. The touch ...

Basic Theory Software Framework Classification 1.B/S: browser/server, thin client 2.C/S: client/server, fat client Http Protocol (Hypertext Transfer Protocol) Agreements: Rules to be complied with by both parties Hypertext transfer protocol: Hypertext transfer protocol Why is it important: The protocol used by the B/S architecture: Char ...

1, Introduction of react Three files need to be imported 1.react.js https://unpkg.com/react@17/umd/react.development.js https://unpkg.com/react-dom@17/umd/react-dom.development.js 2.babel.js (because react is written in xml, it needs to be compiled with babel to avoid error) https://unpkg.com/@babel/standalone/babel.min.js You can direct ...

let keyword declares variable let and var are both used to declare variables but differ Features of let: 1. let cannot repeat declaration; var can repeat declaration 2. let will not be mounted under windows. var is mounted under windows as a property under Windows 3. let is a block-level scope. It does not affect variables in the global sc ...

This article was created on October 8, 2021 at 2010 1. Official layui announcement Today, I just came into contact with layui. It is still necessary for the developers in the background to know the basic front-end programming. Although there are not many front-end programs written in peacetime, they are also annoyed by the tedious fro ...

1. Summary of array methods Method NameRole and Return Values Is the original array changedconcat()Merge the array and return the merged datanojoin()Converts an array to a string and returns it using a delimiternopop()Delete the last bit and return the deleted datayesshift()Delete the first bit and return the deleted datayesunshift()Add one o ...