How to import correctly in nodejs

Node.js is a development platform that allows JavaScript to gain back-end programming capabilities. Unlike JavaScript on the browser side, Node.js can easily reference and use various third-party libraries and plug-ins with the help of NPM (Node.js's own package manager). When using these plug-ins, how to import correctly is a problem that many Node.js developers have to face.

Before learning Node.js and NPM, we must first understand the basic process of using import in Node.js.

First, we need to introduce the third-party library into Node.js and install it into the local environment. Before installation, we need to open the command line tool, enter the directory where the project is located and execute the following command:

npm install 包名

Here, package name refers to the third-party library we need to install. After executing this command, NPM will automatically find the corresponding library from the official package repository of Node.js and install it into the node_modules folder of the project. Taking the installation of the React library as an example, the installation command is as follows:

npm install react

After the installation is completed, we can use the React library in the project. So, how to correctly introduce this library into the project?

The code to introduce the React library into Node.js is as follows:

const React = require('react');

This code means that the React library is introduced into the project and assigned to a file named React variables. In this way, various modules and functions in the React library can be used in the project through the React variable.

It should be noted that the require method in Node.js is used to introduce modules. Before ES6, JavaScript did not have a native module system, so Node.js adopted the CommonJS specification to handle modules. In ES6, JavaScript finally added a native module system and supported the import and export keywords to handle modules. Therefore, in ES6, we can use the following code to introduce the React library:

import React from 'react';

The import keyword here is used to introduce the module, and React is our The name of the module that needs to be imported, from is used to indicate the path where the module we need to import is located. It should be noted that when using import to import a file, the file path must be written in full, otherwise Node.js will not be able to find the file correctly.

Using import to introduce modules has the following advantages compared to using require:

• import Yes Make the code clearer and easier to read, and the structure of the code clearer.
• import can make the code easier to optimize, thereby improving code performance.
• import can avoid naming conflicts.

It should be noted that when using import to introduce modules, we need to pay attention to the following aspects:

• import Must be in top-level scope. The
• import statement must precede require.

To summarize, Node.js is a very easy-to-use back-end development platform that can easily introduce third-party libraries and plug-ins. When using these libraries, we need to abide by the specifications of modular programming and use import or require to introduce modules to ensure that the code has a clear structure, is easy to maintain, and has good performance. Performance.

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