1.7 KiB
1.7 KiB
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Window setTimeout Method |
Window setTimeout Method
The setTimeout()
method calls a function or evaluates an expression after a specified number of milliseconds.
Tips:
- 1000 ms = 1 second.
- The function is only executed once. If you need to repeat execution, use the
setInterval()
method. - Use the
clearTimeout()
method to prevent the function from running.
The syntax of the setTimout()
method is as follows:
setTimeout(function, milliseconds, param1, param2, ...);
For example:
setTimeout(function(){ alert("Hello"); }, 3000);
A very important thing about setTimeout()
is that it will be executed asynchronously. Let's take an example:
console.log("A");
setTimeout(function(){ console.log("B"); }, 0);
console.log("C");
// The order in the console will be
// A
// C
// B
Not as exepected! But we specify only 0 seconds!!! To solve this problem and make sure that our code will execute synchronously we have just to nest the last console in the function
console.log("A");
setTimeout(function() {
console.log("B");
console.log("C");
}, 0);
// The order in the console will be
// A
// B
// C
More Information:
Documentation: MDN
More examples of setTimeout function: w3schools
To understand what really happen under the hood just watch this awesome video Philip Roberts: What the heck is the event loop anyway? | JSConf EU 2014