Javascript’s comment symbol is the dual // at the beginning of the line.

Comments become helpful when writing Javascript. Using the comment function forces the computer to ignore or skip everything else on the line. Comments let us separate sections of the code, write reminders and notes, annotate where snippets came from, and let us disable lines of code for troubleshooting.

Example:

//This is a comment.
//The computer executing Javascript will ignore everything after the dual forward slashes.