JavaScript Occasion.defaultPrevented

Whether or not you began with the previous on_____ property or addEventListener, you recognize that occasions drive person experiences in trendy JavaScript. When you’ve labored with occasions, you recognize that preventDefault() and stopPropagation() are incessantly used to deal with occasions. One factor you most likely did not know: there is a defaultPrevented proptery on occasions!

Think about the next block of code:

// Particular to a hyperlink
const hyperlink = doc.querySelector('#my-link');
hyperlink.addEventListener('click on', e => e.preventDefault());

// A bigger doc scope
doc.addEventListener('click on', documentClickHandler);
operate documentClickHandler(occasion) {
    if (occasion.defaultPrevented) {// Utilizing the property
        // Do one factor if the press has been dealt with
    }
    else {
        // In any other case do one thing recent
    }
}

When preventDefault is named on a given occasion, the defaultPrevented property will get toggled to true. As a consequence of occasion propagation, the occasion bubbles upward with this defaultPrevented worth.

I have been dealing with occasions for twenty years and did not know this property existed till now. What’s nice about defaultPrevented is that it stays with the occasion while not having to trace observe it globally!