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The global setTimeout() method sets a timer which executes a function or specified piece of code once the timer expires.

Syntax

setTimeout( function, milliseconds );

function – a function containing a block of code.
milliseconds – the time after which the function is executed.
The setTimeout() method returns an intervalID, which is a positive integer.

Ex:

//Display a Text Once After 3 Second
// program to display a text using setTimeout method
function greet() {
    console.log('Hello world');
}

setTimeout(greet, 3000);
console.log('This message is shown first');

//Display a Text Once After 3 Second

// program to display a text using setTimeout method

function greet() {

console.log('Hello world');

}

setTimeout(greet, 3000);

console.log('This message is shown first');

Output:

This message is shown first
Hello world

1 2	This message is shown first Hello world

The program displays the text ‘Hello world’ only once after 3 seconds.

Note:
The setTimeout() method is useful when you want to execute a block of once after some time.

Ex:

// program to display time every 3 seconds
function showTime() {

    // return new date and time
    let dateTime= new Date();

    // returns the current local time
    let time = dateTime.toLocaleTimeString();

    console.log(time)

    // display the time after 3 seconds
     setTimeout(showTime, 3000);
}

// calling the function
showTime();

// program to display time every 3 seconds

function showTime() {

// return new date and time

let dateTime= new Date();

// returns the current local time

let time = dateTime.toLocaleTimeString();

console.log(time)

// display the time after 3 seconds

setTimeout(showTime, 3000);

}

// calling the function

showTime();

Output:

5:45:39 PM
5:45:43 PM
5:45:47 PM
5:45:50 PM
..................

5:45:39 PM

5:45:43 PM

5:45:47 PM

5:45:50 PM

..................

The above program displays the time every 3 seconds.

Note:
If you need to execute a function multiple times, it’s better to use the setInterval() method.

clearTimeout()

The program executes a block of code after the specified time interval. If you want to stop this function call, you can use the clearTimeout() method.

Syntax:

clearTimeout( intervalID );

The intervalID is the return value of the setTimeout() method.

Ex:

//Use clearTimeout() Method
// program to stop the setTimeout() method

let count = 0;

// function creation
function increaseCount(){

    // increasing the count by 1
    count += 1;
    console.log(count)
}

let id = setTimeout(increaseCount, 3000);

// clearTimeout
clearTimeout(id); 
console.log('setTimeout is stopped.');

//Use clearTimeout() Method

// program to stop the setTimeout() method

let count = 0;

// function creation

function increaseCount(){

// increasing the count by 1

count += 1;

console.log(count)

}

let id = setTimeout(increaseCount, 3000);

// clearTimeout

clearTimeout(id);

console.log('setTimeout is stopped.');

Output:

setTimeout is stopped.

1	setTimeout is stopped.

Note:
You generally use the clearTimeout() method when you need to cancel the setTimeout() method call before it happens.

You can also pass additional arguments to the setTimeout() method. The syntax is:

setTimeout( function, milliseconds, parameter1, ….paramenterN );

When you pass additional parameters to the setTimeout() method, these parameters (parameter1, parameter2, etc.) will be passed to the specified function.

Ex:

// program to display a name
function greet(name, lastName) {
    console.log('Hello' + ' ' + name + ' ' + lastName);
}

// passing argument to setTimeout
setTimeout(greet, 1000, 'John', 'Doe');

// program to display a name

function greet(name, lastName) {