Event.defaultPrevented - Web APIs 编辑

The defaultPrevented read-only property of the Event interface returns a Boolean indicating whether or not the call to Event.preventDefault() canceled the event.

Syntax

var defaultWasPrevented = event.defaultPrevented;

Value

A Boolean, where true indicates that the default user agent action was prevented, and false indicates that it was not.

Example

This example logs attempts to visit links from two <a> elements. JavaScript is used to prevent the second link from working.

HTML

<p><a id="link1" href="#link1">Visit link 1</a></p>
<p><a id="link2" href="#link2">Try to visit link 2</a> (you can't)</p>
<p id="log"></p>

JavaScript

function stopLink(event) {
  event.preventDefault();
}

function logClick(event) {
  const log = document.getElementById('log');

  if (event.target.tagName === 'A') {
    if (event.defaultPrevented) {
      log.innerText = 'Sorry, but you cannot visit this link!\n' + log.innerText;
    }
    else {
      log.innerText = 'Visiting link...\n' + log.innerText;
    }
  }
}

const a = document.getElementById('link2');
a.addEventListener('click', stopLink);
document.addEventListener('click', logClick);

Result

Specifications

Browser compatibility

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