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The setTimeout() method schedules a function to run after a delay in milliseconds. It is an async operation used to delay code execution without freezing the browser.
Formula
method, you can specify a function to be executed on time - out:Example setTimeout(myFunction, 3000);
function myFunction() {
document.getElementById("demo").innerHTML = "I love You !!";
}
In the example above, myFunction is passed to setTimeout()as an argument. 3000 is the number of milliseconds before myFunction will be called. When you pass a function as an argument, remember not to use parenthesis. Right: setTimeout(myFunction, 3000); Wrong: setTimeout(myFunction(), 3000); Instead of passing a function name as an argument to another function, you can always pass the whole function instead:
Example setTimeout(function() { myFunction("I love You !!!"); }, 3000);
function myFunction(value) {
document.getElementById("demo").innerHTML = value;
}method, you can specify function to be executed for each interval:
Example setInterval(myFunction, 1000);
function myFunction() {
let d = new Date();
document.getElementById("demo").innerHTML=
d.getHours() + ":" +
d.getMinutes() + ":" +
d.getSeconds();
}
In the example above, myFunction is passed to setInterval()as an argument. 1000 is the number of milliseconds between every time myFunction will be called.
A callback runs after another function finishes. Callbacks were the first solution for asynchronous JavaScript.