Understanding how to use !-- ... //-- in JavaScript

Discover what ` !-- ... //-- ` means in JavaScript, how it functions like comments in HTML, and whether it's still used today.
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Understanding <!-- ... //--> in JavaScript

If you've spent any time looking at JavaScript code, you may have come across something that looks a bit strange: the <script> tags with comments that resemble HTML comments. Specifically, you're likely seeing the syntax: <!-- ... //--->. This may raise some questions, especially for those newer to programming or web development. What does this notation mean? Is it necessary? And will you encounter it in modern scripts? Let’s explore these questions in detail.

What is <!-- ... //-->?

The notation <!-- ... //--> is primarily used to create comments within a <script> block in HTML. Here’s a breakdown of the components:

<!--: This starts the comment, just like in HTML.

Content: Any text or code following this marker is treated as a comment and will not be executed when the script is run.

//-->: This concludes the comment, signaling the end of the HTML comment for browsers that might not support JavaScript.

Why Use This Syntax?

Originally, web browsers, especially older ones, had issues when encountering JavaScript code inside <script> tags. The use of <!-- and //--> was a workaround to prevent browsers from attempting to render the JavaScript code as HTML. In a sense, it was a way to ensure compatibility, as some older browsers would misinterpret JavaScript if it were placed directly inside a standard <script> tag without this wrapping.

Modern Usage of <!-- ... //-->

Are We Still Using It Today?

With advances in browser technology, the need for this archaic comment style has largely faded away. Here are some points to consider about current best practices:

Modern Browsers Handle JavaScript natively: Modern browsers do not require this wrapping, as they can distinguish between HTML and JavaScript easily.

Simplicity and Readability: Using the standard JavaScript comment syntax (// for single-line comments and /* ... */ for multi-line comments) makes your code cleaner and more readable.

Recommendation: While you might still see <!-- ... //--> in legacy code or documentation, it’s not advisable to use this practice in new projects. Stick with conventional JavaScript commenting for clarity and adherence to modern coding standards.

Conclusion

In summary, the <!-- ... //---> you find in older JavaScript snippets serves as a method to comment out lines within a script block in an HTML document. Although useful in the past for compatibility reasons, it is no longer a necessary practice in contemporary web development. Instead, developers are encouraged to use standard JavaScript comments for better readability and maintainability of their code.

Embrace the simplicity of modern JavaScript, and leave the outdated commenting techniques behind.