How To Trigger Javascript On Print Event

When it comes to web development, triggering JavaScript on a print event can be a handy way to enhance the user experience of a webpage. In this article, we'll explore how you can accomplish this task seamlessly.

To trigger JavaScript when a user initiates a print event, you need to utilize the `window.onbeforeprint` and `window.onafterprint` events. These two events allow you to execute JavaScript code before and after the printing process happens, respectively.

Here's a simple example demonstrating how you can leverage these events:

window.onbeforeprint = function() {
    // Code to execute before the print dialog appears
    console.log("Printing is about to start!");
};

window.onafterprint = function() {
    // Code to execute after the print dialog closes
    console.log("Printing has finished!");
};

In this code snippet, we set up event listeners for both `onbeforeprint` and `onafterprint` events. You can replace the `console.log` statements with any JavaScript code you wish to run during these print event triggers.

Additionally, you can also use the `window.matchMedia` method to detect when the user is in print preview mode. This can be useful if you need to make specific adjustments to the page layout when the user is previewing the content for printing.

Here's an example of how you might use `matchMedia` to detect print preview:

var mediaQueryList = window.matchMedia('print');

mediaQueryList.addListener(function(mql) {
    if (mql.matches) {
        // User is in print preview mode
        console.log("User is previewing the print layout");
    } else {
        // User has exited print preview mode
        console.log("User has exited print preview");
    }
});

By listening for changes in the media query state, you can adapt your webpage's behavior dynamically based on whether the page is being viewed in print preview mode or not.

In conclusion, harnessing the power of `window.onbeforeprint`, `window.onafterprint`, and `window.matchMedia` events can allow you to create more interactive and user-friendly web experiences when it comes to handling print events in JavaScript. By incorporating these techniques into your web development projects, you can offer users a seamless and tailored printing experience on your webpages.