Comments in JavaScript

JavaScript FAQ | Basic Syntax & General Questions  

Question: How do I insert comments in JavaScript code?

Answer: JavaScript supports three different types of comments:

  1. Multiple-line C-style comments. Everything between /* and */ is a comment, for example: 
    /* This is a comment */
/* C-style comments can span
as many lines as you like,
as shown in this example */
  2. One-line comments of C++ style. These comments begin with // and continue up to the next line break: 
    // This is a one-line comment
  3. One-line comments with the HTML comment-opening sequence (<!--). Note that the JavaScript interpreter ignores the closing characters of HTML comments (-->). Consider this example: 
    <!-- This is treated as a one-line JS comment
<!-- It works just like a comment beginning with //
<!-- --> This is also a one-line JS comment
<!-- --> because JS ignores the closing characters
<!-- --> of HTML-style comments
    HTML-style comments are not usually found in the middle of JavaScript code. (The // comments are simpler and easier to read.) However, they are useful for hiding JavaScript code from old browsers.

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