setTimeout() / clearTimeout()

// Executes a function after the specified delay.
var timerID = setTimeout(function, milliseconds);

// Cancels the timer.
clearTimeout(timerID);

Returns a numeric ID that identifies the timer. Pass this ID to clearTimeout() to cancel the timer.

// Displays a message after 3 seconds.
setTimeout(function() {
	console.log("3 seconds have passed");
}, 3000);

// Example of canceling a timer.
var timerID = setTimeout(function() {
	console.log("This will not run");
}, 5000);
clearTimeout(timerID); // Canceled before it runs.

// To pass arguments, reference variables inside the function.
var name = "Taro";
setTimeout(function() {
	console.log("Hello, " + name + "!"); // Outputs "Hello, Taro!"
}, 1000);

setTimeout() is a timer function that executes a function exactly once after a specified number of milliseconds. It is commonly used to display a message after a page loads, or to delay an action after user interaction.

Because setTimeout() returns a timer ID, you can cancel execution before it fires by passing that ID to clearTimeout(). For example, it is widely used in a technique called "debouncing," where a search operation is delayed while the user is typing and only runs after a certain period of inactivity.

The delay specified in setTimeout() represents the minimum time to wait — execution at exactly that time is not guaranteed. Depending on the browser's workload, the function may run later than specified. If you need to repeat an operation at a fixed interval, use setInterval() instead.