61 lines
1.7 KiB
Markdown
61 lines
1.7 KiB
Markdown
---
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title: Window setTimeout Method
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---
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## Window setTimeout Method
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The `setTimeout()` method calls a function or evaluates an expression after a specified number of milliseconds.
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Tips:
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* 1000 ms = 1 second.
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* The function is only executed once. If you need to repeat execution, use the `setInterval()` method.
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* Use the `clearTimeout()` method to prevent the function from running.
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The syntax of the `setTimout()` method is as follows:
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```js
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setTimeout(function, milliseconds, param1, param2, ...);
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```
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For example:
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```js
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setTimeout(function(){ alert("Hello"); }, 3000);
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```
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A very important thing about `setTimeout()` is that it will be executed asynchronously. Let's take an example:
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```js
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console.log("A");
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setTimeout(function(){ console.log("B"); }, 0);
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console.log("C");
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// The order in the console will be
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// A
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// C
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// B
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```
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**Not as exepected! But we specify only 0 seconds!!!**
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To solve this problem and make sure that our code will execute synchronously we have just to nest the last console in the function
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```js
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console.log("A");
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setTimeout(function() {
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console.log("B");
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console.log("C");
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}, 0);
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// The order in the console will be
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// A
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// B
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// C
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```
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#### More Information:
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Documentation: <a href='https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/setTimeout' target='_blank' rel='nofollow'>MDN</a>
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More examples of setTimeout function: <a href='https://www.w3schools.com/jsref/met_win_settimeout.asp' target='_blank' rel='nofollow'>w3schools</a>
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To understand what really happen under the hood just watch this awesome video
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<a href='https://www.youtube.com/watch?v=8aGhZQkoFbQ' target='_blank' rel='nofollow'>Philip Roberts: What the heck is the event loop anyway? | JSConf EU 2014</a>
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