You really should not use this ever in any situation, but for historical reasons[1], if they are the only thing on the line you can use HTML comments in JavaScr

You really should not use this ever in any situation, but for historical reasons[1], if they are the only thing on the line you can use HTML comments in JavaScript like so: function foo() { <!--- returns true ----> return true; } This works at least in Chrome and V8, not sure about Firefox. [1] https://stackoverflow.com/a/1508005/1888964 https://stackoverflow.com/a/1508005/1888964