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'setInterval' vs 'setTimeout' [duplicate]

Tags:

javascript

People also ask

Is setInterval better than setTimeout?

setTimeout allows us to run a function once after the interval of time. setInterval allows us to run a function repeatedly, starting after the interval of time, then repeating continuously at that interval.

Does setInterval repeat?

Yes, setInterval repeats until you call clearInterval with the interval to stop.

Why do we want sometimes to use setImmediate instead of using setTimeout?

The main advantage to using setImmediate() over setTimeout() is setImmediate() will always be executed before any timers if scheduled within an I/O cycle, independently of how many timers are present.

Is setTimeout CPU intensive?

Using setTimeout and setInterval correctly, can drastical reduce the browsers CPU usage. For instance, using setTimeout instead of using a for or while loop will not only reduce the intensity of CPU usage, but will also guarantee that the browser has a chance to update the UI queue more often.


setTimeout(expression, timeout); runs the code/function once after the timeout.

setInterval(expression, timeout); runs the code/function repeatedly, with the length of the timeout between each repeat.

Example:

var intervalID = setInterval(alert, 1000); // Will alert every second.
// clearInterval(intervalID); // Will clear the timer.

setTimeout(alert, 1000); // Will alert once, after a second.

setInterval fires again and again in intervals, while setTimeout only fires once.

See reference at MDN.


setTimeout():

It is a function that execute a JavaScript statement AFTER x interval.

setTimeout(function () {
    something();
}, 1000); // Execute something() 1 second later.

setInterval():

It is a function that execute a JavaScript statement EVERY x interval.

setInterval(function () {
    somethingElse();
}, 2000); // Execute somethingElse() every 2 seconds.

The interval unit is in millisecond for both functions.


setInterval()

setInterval is a time interval based code execution method that has the native ability to repeatedly run specified script when the interval is reached. It should not be nested into its callback function by the script author to make it loop, since it loops by default. It will keep firing at the interval unless you call clearInterval().

if you want to loop code for animations or clocks Then use setInterval.

function doStuff() {
alert("run your code here when time interval is reached");
}
var myTimer = setInterval(doStuff, 5000);

setTimeout()

setTimeout is a time based code execution method that will execute script only one time when the interval is reached, and not repeat again unless you gear it to loop the script by nesting the setTimeout object inside of the function it calls to run. If geared to loop, it will keep firing at the interval unless you call clearTimeout().

function doStuff() {
alert("run your code here when time interval is reached");
}
var myTimer = setTimeout(doStuff, 5000);

if you want something to happen one time after some seconds Then use setTimeout... because it only executes one time when the interval is reached.


setInterval repeats the call, setTimeout only runs it once.