A timeout in JavaScript is a useful tool to asynchronously delay the execution of the function. It requires 2 arguments: the function that you’d like to set for the async execution, and the delay after which the function will be called.

If you’re new to the timeouts in JavaScript, I suggest starting with reading these tutorials:

Cancel setTimout with clearTimeout

To cancel the scheduled timeout, you should use the function clearTimeout.

The most important thing to remember is that you need a reference to the timeout you’ve set, so that the JavaScript engine knows what to cancel.

Luckily, that’s what’s returned by the function setTimeout.

const timeout = setTimeout(() => console.log('Hello world!'), 1000);


This code logs to the console the timeout object and then the string Hello world! after a delay of one second.

Let’s see what the timeout object looks like:

Timeout {
  _idleTimeout: 1000,
  _idlePrev: [TimersList],
  _idleNext: [TimersList],
  _idleStart: 83,
  _onTimeout: [Function],
  _timerArgs: undefined,
  _repeat: null,
  _destroyed: false,
  [Symbol(refed)]: true,
  [Symbol(kHasPrimitive)]: false,
  [Symbol(asyncId)]: 3,
  [Symbol(triggerId)]: 1

Now, that you know what’s inside, you can add the function clearTimeout to cancel the timeout.

const timeout = setTimeout(() => console.log('Hello world!'), 1000);


In this case, nothing will be printed to the screen as you’ve cancelled the scheduled execution with clearTimeout.