can use the onClick event of a button element to indicate that a function will run when a user
clicks on the button. We define the events in the HTML tags.
Examples of events:
Note: Events are normally used in combination with functions, and the function will not be
executed before the event occurs
The onLoad and onUnload events are triggered when the user enters or leaves the page.
The onLoad event is often used to check the visitor's browser type and browser version, and load
the proper version of the web page based on the information.
Both the onLoad and onUnload events are also often used to deal with cookies that should be set
when a user enters or leaves a page. For example, you could have a popup asking for the user's
name upon his first arrival to your page. The name is then stored in a cookie. Next time the
visitor arrives at your page, you could have another popup saying something like: "Welcome
The onFocus, onBlur and onChange events are often used in combination with validation of form
Below is an example of how to use the onChange event. The checkEmail() function will be called
whenever the user changes Content of the field:
The onSubmit event is used to validate ALL form fields before submitting it.
Below is an example of how to use the onSubmit event. The checkForm() function will be called
when the user clicks the submit button in the form. If the field values are not accepted, the
submit should be cancelled. The function checkForm() returns either true or false. If it returns
true the form will be submitted, otherwise the submit will be cancelled:
onMouseOver and onMouseOut are often used to create "animated" buttons.
Below is an example of an onMouseOver event. An alert box appears when an onMouseOver event is
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