runtime.onConnect

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

BCD tables only load in the browser

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!" });
});

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