javascript annotation@

JavaScript is a commonly used programming language that can be used to create dynamic web page effects and complex interactive applications. When writing JavaScript code, comments are a very important element that can help programmers improve the readability and maintainability of the code. This article will introduce the usage and best practices of JavaScript comments.

1. Types of JavaScript comments

There are two types of comments in JavaScript code: single-line comments and multi-line comments.

Single-line comments start with //, and multiple comments can be included in one line. For example:

// 这是一个单行注释
var x = 10; // 这是一个包含注释的代码行

Multi-line comments start with / and end with /, and can span multiple lines. For example:

/*
这是一个多行注释
它可以跨越多行
*/
var x = 20; /* 这是一个包含注释的代码行 */

2. The role of JavaScript comments

1. Explain the code

Comments can explain the role and purpose of the code. This is helpful to programmers when writing code, and to others when reading code. Sometimes, the code is complex, and comments can make it easier for others to understand it.

2. Ignore Code

Sometimes, you may need to temporarily disable a portion of the code instead of completely removing it. This could be because you need to re-enable the code at some point, or it's simply too complex and you'll need to spend time maintaining it. In this case, annotations are an effective solution.

/*
var x = 10;
var y = 20;
var z = x + y;
*/

In the above example, the definitions of variables x, y and z are commented out so that they will not be executed.

3. Improve the code

Comments can provide suggestions and ideas for code improvement. For example, when adding new functionality, comments can provide guidance on how to add it within existing code. When fixing a bug, comments can help you identify the problem and fix it.

3. Best practices for JavaScript comments

1. Use clear and meaningful comments

Comments should be concise and clear. Your comments should primarily explain the function and purpose of the code. You should avoid useless comments that may confuse or offend other programmers.

2. Reduce comments

Reduce the use of comments as much as possible. As long as the code is clear, comments will naturally be reduced. Most comments should complement the difficulty of reading the code and guide the programmer to read it correctly, rather than presenting the code again in the code.

3. Preface comments with tags

Marking comments can better organize your code and help other programmers understand the entire code correctly. For example, you could separate your code into sections such as "Setup", "Action", "Callback", and "Logout" and comment each section as a markup. Doing so makes it easier for others to find the code snippets they need.

// ============ 设置 ============
var x = 10;
var y = 20;

// ============ 操作 ============
function add(x, y) {
  return x + y;
}

// ============ 回调 ============
function callback() {
  console.log("done!");
}

// ============ 注销 ============
x = null;
y = null;

4. Don’t translate code

When writing code, you may have used some abbreviations and terms. Please make sure not to translate these terms in your comments, as this may cause confusion. You can provide a brief definition in the comment or provide a link to the appropriate documentation or website.

5. Maintaining Comments

Comments may make your code easier to read, but too many comments may also make the code harder to read. Therefore, it is important to promptly update, remove, or modify comments to reflect changes in your code.

4. Conclusion

Comments are a very important element in JavaScript programming. They are used to explain the role and purpose of the code, provide suggestions and ideas, and disable parts of the code when needed. Using labeled comments, maintaining comments, using clear and meaningful comments, and reducing unnecessary comments are all best practices for comments that can help programmers better comment when writing JavaScript code.

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