Remove Code Comments — Strip Comments from JS, CSS, and HTML

Removing Comments from Code

Comment removal is one of the simplest and most effective minification steps. Comments exist only for developer readability and have zero runtime impact, so they can be safely stripped from production builds.

JavaScript Comments

JavaScript has two comment syntaxes:

// Single-line comment

/*
 * Multi-line
 * comment block
 */

/** JSDoc documentation comment */

All three are removed during minification. The tricky part is distinguishing comments from similar-looking syntax:

• Regular expressions: /pattern/g is not a comment, even though it starts with /.
• URLs in strings: "https://example.com" contains // but is not a comment.
• Template literals: Backtick strings may contain // or /* that should be preserved.

A proper comment remover uses a parser (not regex) to correctly handle these cases.

CSS Comments

CSS uses only multi-line comments:

/* This is a CSS comment */

/*!
 * This is a license comment — note the exclamation mark.
 * Many minifiers preserve these by default.
 */

The /*! */ convention signals that a comment should survive minification. This is important for open-source license compliance (e.g., MIT license headers).

HTML Comments

<!-- Standard HTML comment -->

<!--[if IE 9]>
  <link rel="stylesheet" href="ie9.css">
<![endif]-->

Standard comments are removed, but conditional comments (for legacy IE support) may need to be preserved depending on your browser support requirements.

Preserving License Comments

Most build tools provide options to keep license comments:

• Terser: comments: /^!/ or comments: "some" keeps comments with @license or !.
• cssnano: discardComments: { except: /^!/ } preserves /*! */ comments.
• webpack: LicenseWebpackPlugin extracts licenses to a separate file.

Size Impact

Comments often account for 10-30% of source file size, especially in well-documented codebases. JSDoc-heavy libraries can have more comment characters than actual code.