HTML beforematch DOM Event: Reference and Examples

When someone interacts with a webpage, the browser sends events to the relevant JavaScript code. The beforematch event happens when a hidden-until-found region is about to be revealed by find-in-page.

When beforematch happens

A hidden-until-found region is about to be revealed by find-in-page.

You can listen for it using addEventListener(). That keeps event handling separate from HTML attributes such as onclick and works well with modern code organization.

A small working example

<p hidden="until-found" id="demo-target">Search for hidden lesson notes</p>
<p id="event-status" role="status">Waiting for beforematch...</p>
<script>
    const eventTarget = document.getElementById("demo-target");
    const eventStatus = document.getElementById("event-status");

    if (eventTarget) {
        eventTarget.addEventListener("beforematch", (eventDetails) => {
            eventStatus.textContent = "beforematch event received";
            console.log(eventDetails.type, eventDetails.target);
        });
    }
</script>

Reading the code

The browser listens for beforematch on the relevant target. When the event occurs, the callback receives eventDetails, updates the status message and logs the event name and target in Developer Tools.

Put text inside hidden="until-found", then search for that text in a supporting browser.

Some events need a specific browser condition, another tab or window, or a Web Component to reproduce. Read the trigger steps carefully before deciding that an event handler is not working.

Try it in your browser

Open the page, show the Console panel, and follow this test: Put text inside hidden="until-found", then search for that text in a supporting browser. Then change one thing in the example and observe whether the event still fires.

Common Beginner Mistakes

• Expecting beforematch to fire without its required user action or browser condition.
• Put text inside hidden="until-found", then search for that text in a supporting browser.
• Adding repeated event listeners without considering cleanup or unwanted side effects.

Key Takeaways

• beforematch reports a hidden-until-found region is about to be revealed by find-in-page.
• addEventListener("beforematch", ...) listens for the event on the appropriate target.
• Put text inside hidden="until-found", then search for that text in a supporting browser.