How is a single-line comment written in JavaScript?

In JavaScript, a single-line comment is initiated with the double forward slashes // followed by the comment text. This format tells the JavaScript interpreter to ignore everything on that line after the slashes, allowing developers to insert notes or explanations into their code without affecting program execution.

Using // is a widely accepted practice in JavaScript for adding concise comments that do not require additional detail. It enables programmers to annotate their code efficiently, making it easier to understand for anyone reviewing it later.

The other formats presented do not represent single-line comments in JavaScript. The first option, which uses /* and / is intended for multi-line comments. The third option, /* and */ is also a multi-line comment style, often used for documentation comments in JavaScript but still does not pertain to single-line comments. The last option with a hash mark (#) is not recognized as a comment style in JavaScript and is used in other programming languages, such as Python. Thus, the double forward slashes are the correct syntax for single-line comments in JavaScript.