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Dillion Megida
Dillion Megida

Posted on • Updated on

How to cancel a setTimeout in JavaScript

setTimeout in JavaScript is a native function that sets a function to be executed when a specified timer completes.

Here's the syntax:

setTimeout(function, timer)
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timer is in milliseconds. Here's an example where we do something after two seconds:

setTimeout(() => {
  console.log("hey...I'm 2 seconds in")
}, 2000}
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Cancelling a setTimeout

You may not want a setTimeout to complete for various reasons. One reason can be cleaning up side-effects in React useEffect. So how do you stop it? Here's how...

The setTimeout function returns an id when declared:

const timeoutId = setTimeout(() => {}, 1000)
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With this id and the clearTimeout JavaScript function, you can cancel a setTimeout.

Here's the syntax of the clearTimeout function:

clearTimeout(timeoutId)
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With this, we can have:

const timeoutId = setTimeout(() => {
  console.log("hey...I'm 2 seconds in"
}, 2000}

// later on

clearTimeout(timeoutId)
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If the setTimeout declaration has not been completed, the clearTimeout function will cancel it, and the callback function will not be executed anymore.

Discussion (4)

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curiousdev profile image
CuriousDev

Thanks, this is short and useful!

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dillionmegida profile image
Dillion Megida Author

I'm glad you found it useful :)

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leonardofrp5 profile image
Leonaro Romero Perez

Nice

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yomassive profile image
Andrew Belykh

wow