How Can JavaScript be Used to Prevent Page Navigation?

Preventing Webpage Navigation using JavaScript

When a user attempts to navigate away from a webpage, various events are triggered in the browser. These events can be utilized using JavaScript to display messages or perform actions before the navigation occurs.

How to prevent navigation using JavaScript:

Using the onunload Event:

While the onunload event allows for displaying messages, it cannot interrupt navigation as it is triggered after the page has already started loading.

Using the onbeforeunload Event:

The onbeforeunload event is triggered before the browser navigates away from the page. It allows you to interrupt navigation with a prompt or message.

`window.onbeforeunload = function() {
return "";
}`;

Note: An empty string is returned here because modern browsers display a default message that cannot be overridden.

Specifying a Message in Older Browsers:

In older browsers, you can specify the message to display in the prompt using the onbeforeunload event:

`window.onbeforeunload = function() {
return "Are you sure you want to navigate away?";
}`;

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