JavaScript Events
HTML events are "things" that happen to HTML
elements.
When JavaScript is used in HTML pages, JavaScript can
"react" on these events.
HTML Events
An HTML event can be something the browser does, or something
a user does.
Here are some examples of HTML events:
An HTML web page has finished loading
An HTML input field was changed
An HTML button was clicked
Often, when events happen, you may want to do something.
JavaScript lets you execute code when events are detected.
HTML allows event handler attributes, with JavaScript code,
to be added to HTML elements.
With single quotes:
<some-HTML-element some-event='some
JavaScript'>
With double quotes:
<some-HTML-element some-event="some
JavaScript">
In the following example, an onclick attribute (with code),
is added to a button element:
Example
<button
onclick="document.getElementById('demo').innerHTML = Date()">The
time is?</button>
»
In the example above, the JavaScript code changes the content
of the element with id="demo".
In the next example, the code changes the content of its own
element (using this.innerHTML):
Example
<button onclick="this.innerHTML =
Date()">The time is?</button>
»
JavaScript code is often several lines long. It is more
common to see event attributes calling functions:
Example
<button
onclick="displayDate()">The time is?</button>
»
Common HTML Events
Here is a list of some common HTML events:
Event Description
onchange An HTML
element has been changed
onclick The user
clicks an HTML element
onmouseover The user
moves the mouse over an HTML element
onmouseout The user
moves the mouse away from an HTML element
onkeydown The user
pushes a keyboard key
onload The browser
has finished loading the page
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