onfocus
Event
Tóm Tắt
Example
Execute a JavaScript when an input field gets focus:
<input type=”text”
onfocus=”myFunction()”>
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More “Try it Yourself” examples below.
Definition and Usage
The onfocus event occurs when an element gets focus.
The onfocus event is most often used with <input>, <select>, and <a>.
Tip: The onfocus event is the opposite of the
onblur event.
Tip: The onfocus event is similar to the
onfocusin event.
The main difference is that the onfocus event does not bubble. Therefore, if
you want to find out whether an element or its child gets the focus, you could
use the onfocusin event. However, you can achieve this by using
the optional useCapture parameter
of the addEventListener()
method for the onfocus event.
Browser Support
Event
onfocus
Yes
Yes
Yes
Yes
Yes
Syntax
In HTML:
<element onfocus=”myScript“>
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In JavaScript:
object.onfocus = function(){myScript};
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In JavaScript, using the addEventListener() method:
object.addEventListener(“focus”, myScript);
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Technical Details
Bubbles:
No
Cancelable:
No
Event type:
FocusEvent
Supported HTML tags:
ALL HTML elements, EXCEPT: <base>, <bdo>, <br>, <head>, <html>, <iframe>, <meta>, <param>, <script>, <style>, and <title>
DOM Version:
Level 2 Events
More Examples
Example
Using “onfocus” together with the “onblur” event:
<input type=”text” onfocus=”focusFunction()” onblur=”blurFunction()”>
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Example
Clear input field on focus:
<!– When the input field gets focus, replace its current value with an
empty string –>
<input type=”text” onfocus=”this.value=”” value=”Blabla”>
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Example
Event delegation: setting the useCapture parameter of
addEventListener() to true:
<form id=”myForm”>
<input type=”text” id=”myInput”>
</form>
<script>
var x = document.getElementById(“myForm”);
x.addEventListener(“focus”, myFocusFunction, true);
x.addEventListener(“blur”, myBlurFunction, true);
function myFocusFunction() {
document.getElementById(“myInput”).style.backgroundColor = “yellow”;
}
function myBlurFunction() {
document.getElementById(“myInput”).style.backgroundColor = “”;
}
</script>
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Example
Event delegation: using the focusin event (not supported
by Firefox):
<form id=”myForm”>
<input type=”text” id=”myInput”>
</form>
<script>
var x = document.getElementById(“myForm”);
x.addEventListener(“focusin”, myFocusFunction);
x.addEventListener(“focusout”, myBlurFunction);
function myFocusFunction() {
document.getElementById(“myInput”).style.backgroundColor = “yellow”;
}
function myBlurFunction() {
document.getElementById(“myInput”).style.backgroundColor = “”;
}
</script>
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