| 摘要 |
A web page may initiate communication with a browser toolbar. In one example, the web page contains an invisible iframe, and code that causes the iframe to load a specific Uniform Resource Locator ("URL"). When the iframe loads that URL, it generates an onload event. The toolbar may subscribe to the iframe's onload event, and may contain a handler for that event. When the page wants to send a message to the toolbar, the page adds the message to a URL and then executes the code that causes the iframe to load that URL, thereby generating an onload event. The handler in the toolbar receives the onload event, and extracts the message from the URL. The handler may then execute additional code to perform an action in response to the message.
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