> ## Documentation Index > Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt > Use this file to discover all available pages before exploring further. # JavaScript Single-line Comment A single-line comment in JavaScript is a lexical construct that instructs the JavaScript parser to ignore a specific sequence of characters, omitting them from the execution context during the tokenization phase. ## Syntax and Parsing Mechanics A single-line comment is initiated by the double forward-slash token (`//`). The JavaScript engine ignores all characters following this token up to the next `LineTerminator` (such as a line feed `\n`, carriage return `\r`, line separator `\u2028`, or paragraph separator `\u2029`). ```javascript theme={"dark"} // The parser ignores all characters on this line let x = 10; ``` ## Placement Single-line comments can be declared as standalone lines or appended to the end of a valid JavaScript statement. When appended inline, the parser evaluates the preceding code and ignores everything from the `//` token onward. ```javascript theme={"dark"} let y = 20; // The parser evaluates 'let y = 20;' and ignores this text ``` ## Lexical Boundaries Because the single-line comment is strictly terminated by a `LineTerminator`, it cannot span multiple lines. Any text on a subsequent line is treated as standard executable code by the engine unless it is preceded by another `//` token. ```javascript theme={"dark"} // The parser ignores this line let z = 30; // The parser evaluates the declaration, then ignores the rest of the line // The parser ignores this line as well ``` If a `//` token is placed inside a string literal or a regular expression, it is evaluated as standard character data rather than a comment initiator. ```javascript theme={"dark"} let path = "https://example.com"; // The first '//' is part of the string literal ```

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