JavaScript Event.defaultPrevented

Whether you started with the old on_____ property or addEventListener, you know that events drive user experiences in modern JavaScript. If you’ve worked with events, you know that preventDefault() and stopPropagation() are frequently used to handle events. One thing you probably didn’t know: there’s a defaultPrevented proptery on events!

Consider the following block of code:

// Specific to a link
const link = document.querySelector('#my-link');
link.addEventListener('click', e => e.preventDefault());

// A larger document scope
document.addEventListener('click', documentClickHandler);
function documentClickHandler(event) {
    if (event.defaultPrevented) {// Using the property
        // Do one thing if the click has been handled
    }
    else {
        // Otherwise do something fresh
    }
}

When preventDefault is called on a given event, the defaultPrevented property gets toggled to true. Due to event propagation, the event bubbles upward with this defaultPrevented value.

I’ve been handling events for two decades and didn’t know this property existed until now. What’s great about defaultPrevented is that it stays with the event without needing to track track it globally!

  • Tips for Starting with Bitcoin and Cryptocurrencies

    One of the most rewarding experiences of my life, both financially and logically, has been buying and managing cryptocurrencies like Bitcoin, Litecoin, Ethereum. Like learning any other new tech, I made rookie mistakes along the way, but learned some best practices along the way. Check out…

  • How I Stopped WordPress Comment Spam

    I love almost every part of being a tech blogger:  learning, preaching, bantering, researching.  The one part about blogging that I absolutely loathe:  dealing with SPAM comments.  For the past two years, my blog has registered 8,000+ SPAM comments per day.  PER DAY.  Bloating my database…

  • Spatial Navigation

    Spatial navigation is the ability to navigate to focusable elements based on their position in a given space.  Spatial navigation is a must when your site or app must respond to arrow keys, a perfect example being a television with directional pad remote.  Firefox OS TV apps are simply…

  • Highlighter: A MooTools Search & Highlight Plugin

    Searching within the page is a major browser functionality, but what if we could code a search box in JavaScript that would do the same thing? I set out to do that using MooTools and ended up with a pretty decent solution. The MooTools JavaScript Class The…

David Walsh
Source link