How to code nodejs

Node.js is a very popular JavaScript runtime environment for the development of server-side applications. It can write server-side code using JavaScript, which avoids using different languages ​​to write server-side and client-side code, making the entire web application simpler and easier to maintain. In this article, we will discuss coding in Node.js and how to follow best practices to write high-quality Node.js code.

1. Choose the right editor

First of all, when choosing an editor, you should give priority to the editor that works with Node.js. The most commonly used editor for Node.js is Visual Studio Code, but other editors can also be used, such as Sublime Text, Atom, etc.

2. Follow coding conventions

Node.js follows the same coding conventions as JavaScript because Node.js is basically a wrapper around JavaScript. Therefore, for Node.js coding, the same coding conventions as for JavaScript apply.

Here are some coding conventions worth paying attention to:

• Indentation: Usually use 2 spaces to indent code blocks, which can increase the readability of the code.
• Brackets: For the placement of braces at the beginning or end of a block, it is recommended to place the braces at the end to make the code clearer.
• Semicolon: When writing code, you should always use semicolons.
• Variable and function naming: Variable and function naming should be descriptive and as clear as possible. Avoid using abbreviations or meaningless words.

3. Importing modules

Node.js is built on the concept of modules, which means that writing high-quality code must use the correct modules.

To import a module, you can use the const keyword to declare variables. For example, the code to import the express module is as follows:

const express = require('express');

In this example, we use the require() function to import the express module and assign it to a constant named express.

4. Using Promise

Node.js is event-based programming, which means it avoids problems such as deadlocks and blocking in synchronous programming. It uses callback functions to handle events as well as asynchronous programming.

However, callback functions may lead to callback hell. To avoid this problem, we can use Promise. Promises are a cleaner, more readable and easier to maintain way to deal with asynchronous programming.

The following is an example of using Promise:

function getFileData(filePath) {
  return new Promise((resolve, reject) => {
    fs.readFile(filePath, 'utf8', (err, data) => {
      if (err) reject(err);

      resolve(data);
    });
  });
}

getFileData('./myfile.txt')
  .then(data => console.log(data))
  .catch(err => console.error(err));

In this example, we create a function getFileData() that returns Promise to read the file content. With Promise, we can easily handle success and failure situations using then() and catch().

5. Using ESLint

ESLint is a static code analyzer that can help us find and fix common code errors and potential defects when writing JavaScript code. ESLint supports Node.js, so we can use it to help us write high-quality Node.js code.

To use ESLint, you must first install it. ESLint can be installed from npm with the following command:

npm install eslint --save-dev

After installation, you need to configure a .eslintrc.json file, which specifies the checking rules of ESLint.

{
  "env": {
    "node": true,
    "es6": true
  },
  "extends": "eslint:recommended",
  "rules": {
    "no-console": "off",
    "indent": ["error", 2],
    "linebreak-style": ["error", "unix"],
    "semi": ["error", "always"]
  }
}

In this example, we define a standard configuration that disables the use of console, specifies indentation to be 2 spaces, specifies line breaks to be UNIX type, and specifies that semicolons must be used.

6. Using unit testing

Unit testing is a type of testing designed to test a single component or unit of an application. This type of testing helps catch bugs during development and quickly confirm whether changes break the behavior of existing code.

Node.js supports multiple testing frameworks, including Mocha, Jasmine, and Jest. Using these frameworks, we can easily write unit tests against different Node.js libraries and applications.

The following is the code to implement a simple unit test using Mocha and Chai:

const assert = require('chai').assert;
const app = require('../app');

describe('App', function() {
  it('app should return hello', function() {
    assert.equal(app(), 'hello');
  });
});

In this example, we use the Chai assertion library to write the actual tests, while Mocha is used to manage the tests and generate test reports.

7. Conclusion

Node.js coding needs to follow the same coding conventions as JavaScript. In addition to this, you should import modules correctly, use Promise and asynchronous programming, use ESLint for code analysis and use unit tests for testing.

These methods can help us write high-quality, fully functional and easy-to-maintain Node.js code.

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