What javascript can and cannot be used

JavaScript is a popular and powerful programming language that is widely used in web development, game development, mobile application development and other fields. JavaScript has many features that can and cannot be used, which are discussed in detail below.

1. What JavaScript can do

1. Dynamic web page interaction

JavaScript was first designed for web page interaction, which is also its most common application. Through JavaScript, interactive effects such as clicking a button to pop up an information box, form submission verification, carousel revolving lantern, etc. can be achieved. Dynamic effects can make web pages more lively and interesting, and also enhance the interaction between users and web pages.

2. Front-end development

Front-end development is very popular now, and JavaScript is an indispensable part. From the structural style of web pages to data logic processing, JavaScript can realize it. JavaScript frameworks, such as React, Angular, Vue, etc., can be used for front-end development. Frameworks can simplify code and improve development efficiency.

3. WeChat Mini Program Development

WeChat Mini Program is a very popular mobile application, and the programming language of WeChat Mini Program is JavaScript. The explanation given by the WeChat team is: JavaScript is one of the most popular programming languages in the world. It is easy to develop and learn, and is in line with the original intention of small program development. Using JavaScript you can quickly develop efficient small programs.

4. Game Development

JavaScript is not only widely used in web development, it is also popular in game development. Use JavaScript to develop fun and interactive games with HTML5 and Canvas. Frameworks such as Phaser and PixiJS can make game production faster and provide a better experience.

5. Server-Side Development

Although JavaScript was originally designed to be executed in the client browser, there are now many frameworks that can use JavaScript to execute on the server side. Node.js is the best-known server-side JavaScript execution environment that can handle I/O-intensive tasks.

2. Things that JavaScript cannot do

1. Operation of local files on the computer

Due to security policy restrictions, JavaScript is not allowed to access local files on the computer. Calling system API, etc. is to protect the user's information security. This means that if you need to handle local files in the browser client, you may need to use an appropriate plugin or library, such as jQuery File Upload, DropzoneJS.

2. Directly operate the database

JavaScript cannot directly access the database and cannot directly perform database operations, but it can use Node.js on the server side to operate the database. Node.js integrates with various database drivers and can be used to operate MySQL, MongoDB and other databases.

3. Cannot perform time-consuming tasks

JavaScript is a single-threaded language, so it cannot perform time-consuming operations, such as image processing, which requires a large amount of data calculations, etc., so it is not suitable Done in JavaScript. These tasks may need to be written in other languages, such as C, etc.

4. Cannot perform file IO operations

JavaScript runs in the browser's sandbox, and its security policy restricts the browser from reading and writing files locally on the computer. . If you need to operate files, use Node.js on the server side. Use the fs module in Node.js to easily read and write files.

Summary

To sum up, JavaScript has many features that can and cannot be used. JavaScript can be used for dynamic web page interaction, front-end development, WeChat applet development, game development and server-side development. However, JavaScript cannot directly access the database, and cannot perform local file operations, time-consuming tasks, file IO and other operations on the client side. Developers should choose the appropriate programming language and technology to complete the task based on project needs.

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