How Can I Detect Changes in an iFrame\'s Source Attribute?

Detecting iFrame Source Changes

As a web developer, you may encounter situations where you need to monitor changes in the source attribute of an embedded iFrame. Whether it's for analytics or ensuring responsiveness, detecting these changes is essential.

Fortunately, there are several ways to approach this challenge:

OnLoad Event

One effective approach is to utilize the onLoad event listener within the iFrame. This event fires whenever the content within the iFrame has finished loading. By attaching a handler to this event, you can execute code to monitor any changes in the src attribute.

For example:

<iframe src="http://example.com" onLoad="checkSrc()"></iframe>

ContentWindow Access (Same Domain)

If the iFrame content belongs to the same domain as the parent page, you can leverage the contentWindow property to access the iFrame's window object. This allows you to directly interact with the iFrame's location object and track source changes.

For example:

<iframe src="/test.html" onLoad="alert(this.contentWindow.location)"></iframe>

Polling

As a last resort, you can implement a polling mechanism to periodically check the iFrame's src attribute. While not ideal from a performance perspective, this approach can still be effective for detecting source changes, especially when other options are unavailable.

For example:

function checkSrc() {
  // Get the current iFrame source.
  var src = iframe.src;

  // Check if the source has changed.
  if (src !== previousSrc) {
    // Update previous source and do something.
    previousSrc = src;
    // ...
  }

  // Schedule the next check.
  setTimeout(checkSrc, 1000);
}

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