What are the iframe listening events?

iframe listening events include onload event, onunload event, onbeforeunload event, onmessage event and onerror event, etc. Detailed description: 1. Add an onload event, which is triggered when the content in the iframe is loaded; 2. Add an onunload event, which is triggered when the content in the iframe is unloaded; 3. Add an onbeforeunload event, which is triggered before the content in the iframe is unloaded. etc.

# Operating system for this tutorial: Windows 10 system, Dell G3 computer.

iframe is a tag in HTML that allows other web pages or documents to be embedded in a web page. By using iframe, we can embed other web pages or documents into the current page, thereby achieving page nesting and interaction.

When using iframe, we can control and interact with iframe by listening to different events. The following are some common iframe events:

1. onload event: Triggered when the content in the iframe is loaded. You can listen to this event by adding the onload attribute to the iframe tag, for example:

<iframe src="example.html" onload="iframeLoaded()"></iframe>

In the above code, when the content in the iframe is loaded, the function named iframeLoaded will be called.

2. onunload event: Triggered when the content in the iframe is unloaded. You can listen to this event by adding the onunload attribute to the iframe tag, for example:

<iframe src="example.html" onunload="iframeUnloaded()"></iframe>

In the above code, when the content in the iframe is unloaded, the function named iframeUnloaded will be called.

3. onbeforeunload event: Triggered before the content in the iframe is unloaded. You can listen to this event by adding the onbeforeunload attribute to the iframe tag, for example:

<iframe src="example.html" onbeforeunload="iframeBeforeUnload()"></iframe>

In the above code, when the content in the iframe is about to be unloaded, the function named iframeBeforeUnload will be called.

4. onmessage event: Triggered when the content in the iframe sends a message to the parent page. You can listen to this event by using the window.addEventListener method in the parent page, for example:

window.addEventListener("message", receiveMessage, false);
function receiveMessage(event) {
  // 处理接收到的消息
}

In the above code, when the content in the iframe sends a message to the parent page, a function named receiveMessage will be called. Process the received message.

5. onerror event: Triggered when the content in the iframe fails to load. You can listen to this event by adding the onerror attribute to the iframe tag, for example:

<iframe src="example.html" onerror="iframeError()"></iframe>

In the above code, when the content in the iframe fails to load, a function named iframeError will be called.

By listening to these events, we can control and interact with the loading, unloading, messaging, etc. of iframes, thereby achieving richer web page functions and user experience.

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