CodeHS Glossary

Comment Out JavaScript

For a longer explanation on comments, see here.

Commenting out code makes the computer ignore it, so it does not run.

The computer ignores lines of code that begin with // or that are in between /* and */

Sometimes, you want to test a version of your code but not run all of it. Instead of deleting your code to re-write it later, you can just comment out some of your code like this:

function start() {
    setup();
    doFirstThing();
    // doSecondThing();
}

This program will not run the doSecondThing(); function, since it is commented out. This lets you just test your program’s setup() and doFirstThing() functions.

You can also comment out many lines at once using multiline comments like this:

move();
move();
putBall();
move();
turnLeft();
putBall();
/*
move();
move();
turnLeft();
putBall();
move();
turnLeft();
*/

The above code will only run the first 6 commands and skip the rest, since they are commented out using /* and */