In JavaScript, the setTimeout() function is utilized to introduce a delay or to execute a particular function after a specified amount of time has passed. It is part of the Web APIs provided by browsers and Node.js, allowing asynchronous execution of code.
Syntax:
setTimeout(function, milliseconds, arg1, arg2, ...);Parameters:
- function: After the specified time period, this is the function that is executed.
- milliseconds: The delay time is expressed in milliseconds.
- arg1, arg2: If needed, these are the optional parameters.
Cancellation of setTimeout()
JavaScript provides a corresponding function called clearTimeout() to cancel a scheduled timeout before it gets executed.
Example: In this example, we have shown the cancellation of settimeout..
function delayedFunction() {
console.log("This won't be executed due to clearTimeout");
}let timeoutId = setTimeout(delayedFunction, 2000);// Cancel the setTimeout before it executesclearTimeout(timeoutId);console.log("Timeout canceled");
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Purpose of setTimeout()
In JavaScript, the setTimeout() function is utilized to introduce a delay or to execute a particular function after a specified amount of time has passed. It is part of the Web APIs provided by browsers and Node.js, allowing asynchronous execution of code.
Example: Below is the example of settimeout.
console.log("Start");
setTimeout(function() {
console.log("Delayed log after 2000 milliseconds");
}, 2000);console.log("End");
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Output:
Start
End
Delayed log after 2000 milliseconds
Explanation:
-
The
setTimeout()function takes two parameters: a callback function and a time delay in milliseconds. -
In the example, after the initial “Start” and “End” logs, the
setTimeout()is set to execute the callback function (delayed log) after 2000 milliseconds (2 seconds). -
The rest of the code continues executing without waiting for the delay, demonstrating the asynchronous nature of
setTimeout(). - After the specified delay, the callback function is invoked, resulting in the “Delayed log after 2000 milliseconds” message being logged to the console.
Use Cases:
- Delaying Execution: It can be used to introduce delays in code execution, useful for scenarios like animations, timed events, or deferred operations.
- Asynchronous Operations: When combined with callback functions, it facilitates asynchronous behavior, enabling non-blocking code execution.
- Timeouts in Web Development: It’s commonly employed in web development for handling timeouts, such as showing a notification after a certain time or refreshing content.