A
Port
object represents one end of a connection between two specific contexts, which can be used to exchange messages.
One side initiates the connection, using a
connect()
API. This returns a
Port
object. The other side listens for connection attempts using an
onConnect
listener. This is passed a corresponding
Port
对象。
Once both sides have
Port
objects, they can exchange messages using
Port.postMessage()
and
Port.onMessage
. When they are finished, either end can disconnect using
Port.disconnect()
, which will generate a
Port.onDisconnect
event at the other end, enabling the other end to do any cleanup required.
You can use this pattern to communicate between:
You need to use different connection APIs for different sorts of connections, as detailed in the table below.
| Connection type | Initiate connection attempt | Handle connection attempt |
|---|---|---|
| Background script to content script |
tabs.connect()
|
runtime.onConnect
|
| Content script to background script |
runtime.connect()
|
runtime.onConnect
|
| Extension to native application |
runtime.connectNative()
|
Not applicable (see Native messaging ). |
| Extension to Extension |
runtime.connect()
|
runtime.onConnectExternal
|
Values of this type are objects. They contain the following properties:
名称
string
. The port's name, defined in the
runtime.connect()
or
tabs.connect()
call that created it. If this port is connected to a native application, its name is the name of the native application.
disconnect
function
. Disconnects a port. Either end can call this when they have finished with the port. It will cause
onDisconnect
to be fired at the other end. This is useful if the other end is maintaining some state relating to this port, which can be cleaned up on disconnect. If this port is connected to a native application, this function will close the native application.
error
对象
. If the port was disconnected due to an error, this will be set to an object with a string property
message
, giving you more information about the error. See
onDisconnect
.
onDisconnect
对象
. This contains the
addListener()
and
removeListener()
functions common to all events for extensions built using WebExtension APIs. Listener functions will be called when the other end has called
Port.disconnect()
. This event will only be fired once for each port. The listener function will be passed the
Port
object. If the port was disconnected due to an error, then the
Port
argument will contain an
error
property giving more information about the error:
port.onDisconnect.addListener((p) => {
if (p.error) {
console.log(`Disconnected due to an error: ${p.error.message}`);
}
});
Note that in Google Chrome
port.error
is not supported: instead, use
runtime.lastError
to get the error message.
onMessage
对象
. This contains the
addListener()
and
removeListener()
functions common to all events for extensions built using WebExtension APIs. Listener functions will be called when the other end has sent this port a message. The listener will be passed the value that the other end sent.
postMessage
function
. Send a message to the other end. This takes one argument, which is a serializable value (see
Data cloning algorithm
) representing the message to send. It will be delivered to any script listening to the port's
onMessage
event, or to the native application if this port is connected to a native application.
sender
可选
runtime.MessageSender
. Contains information about the sender of the message. This property will only be present on ports passed to
onConnect
/
onConnectExternal
listeners.
BCD tables only load in the browser
This content script:
Port
in a variable called
myPort
.
myPort
and logs them.
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:
portFromCS
.
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!"});
});
If you have multiple content scripts communicating at the same time, you might want to store each connection in an array.
// background-script.js
var ports = []
function connected(p) {
ports[p.sender.tab.id] = p
//...
}
browser.runtime.onConnect.addListener(connected)
browser.browserAction.onClicked.addListener(function() {
ports.forEach(p => {
p.postMessage({greeting: "they clicked the button!"})
})
});
This example connects to the native application "ping_pong" and starts listening for messages from it. It also sends the native application a message when the user clicks a browser action icon:
/*
On startup, connect to the "ping_pong" app.
*/
var port = browser.runtime.connectNative("ping_pong");
/*
Listen for messages from the app.
*/
port.onMessage.addListener((response) => {
console.log("Received: " + response);
});
/*
On a click on the browser action, send the app a message.
*/
browser.browserAction.onClicked.addListener(() => {
console.log("Sending: ping");
port.postMessage("ping");
});
注意：
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.
最后修改： , 由 MDN 贡献者