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当使用扩展处理或content script建立连接时触发.

Syntax

browser.runtime.onConnect.addListener(listener)
browser.runtime.onConnect.removeListener(listener)
browser.runtime.onConnect.hasListener(listener)

事件有三个方法:

addListener(callback)
为 这个事件添加一个监听器.
removeListener(listener)
停止监听这个事件. listener 参数就是要移除的监听器.
hasListener(listener)
检查监听器是否已经注册到这个事件上. 如果已经监听,则返回 true 否则返回 false.

addListener 语法

参数

function

A callback function that will be called when this event occurs. The function will be passed the following arguments:

port
A runtime.Port object connecting the current script to the other context it is connecting to.

Browser compatibility

ChromeEdgeFirefoxFirefox for AndroidOpera
Basic support26 Yes454815

Examples

This content script:

  • connects to the background script, and stores the Port in a variable myPort
  • listens for messages on myPort, and logs them
  • sends messages to the background script, using myPort, when the user clicks the document
// content-script.js

var myPort = browser.runtime.connect({name:"port-from-cs"});
myPort.postMessage({greeting: "hello from content script"});

myPort.onMessage.addListener(function(m) {
  console.log("In content script, received message from background script: ");
  console.log(m.greeting);
});

document.body.addEventListener("click", function() {
  myPort.postMessage({greeting: "they clicked the page!"});
});

The corresponding background script:

  • listens for connection attempts from the content script
  • when it receives a connection attempt:
    • stores the port in a variable named portFromCS
    • sends the content script a message using the port
    • starts listening to messages received on the port, and logs them
  • sends messages to the content script, using portFromCS, when the user clicks the extension's browser action
// background-script.js

var portFromCS;

function connected(p) {
  portFromCS = p;
  portFromCS.postMessage({greeting: "hi there content script!"});
  portFromCS.onMessage.addListener(function(m) {
    console.log("In background script, received message from content script")
    console.log(m.greeting);
  });
}

browser.runtime.onConnect.addListener(connected);

browser.browserAction.onClicked.addListener(function() {
  portFromCS.postMessage({greeting: "they clicked the button!"});
});

Example extensions

Acknowledgements

This API is based on Chromium's chrome.runtime API. This documentation is derived from runtime.json in the Chromium code.

Microsoft Edge compatibility data is supplied by Microsoft Corporation and is included here under the Creative Commons Attribution 3.0 United States License.

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