SendMessage 从扩展后台或弹出到内容脚本无法工作

我知道这个问题已经被以不同的方式反复提出，但是我试着去回答所有的问题(希望我没有错过任何人) ，但是没有一个对我有用。

这是我的分机号码:

舱单:

{
"name": "test",
"version": "1.1",
"background":
{
"scripts": ["contextMenus.js"]
},


"permissions": ["tabs", "<all_urls>", "contextMenus"],


"content_scripts" : [
{
"matches" : [ "http://*/*" ],
"js": ["jquery-1.8.3.js", "jquery-ui.js"],
"css": [ "jquery-ui.css" ],
"js": ["openDialog.js"]
}
],


"manifest_version": 2
}

ContextMenus.js

function onClickHandler(info, tab) {
if (info.menuItemId == "line1"){


alert("You have selected: " + info.selectionText);


chrome.extension.sendMessage({action:'open_dialog_box'}, function(){});


alert("Req sent?");


}
}


chrome.contextMenus.onClicked.addListener(onClickHandler);


chrome.runtime.onInstalled.addListener(function() {


chrome.contextMenus.create({"id": "line1", "type": "normal", "title": "I'm line 1",     "contexts":["selection"]});


});

OpenDialog.js

chrome.extension.onMessage.addListener(function(msg, sender, sendResponse) {


if (msg.action == 'open_dialog_box') {
alert("Message recieved!");
}
});

后台页面的两个警报可以正常工作，而 content _ script 中的一个警报不能正常工作。

控制台日志消息: 端口错误: 无法建立连接。接收端不存在。

我的错在哪里？

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小开
最佳答案

In your background page you should call

chrome.tabs.query({active: true, currentWindow: true}, function(tabs){
chrome.tabs.sendMessage(tabs[0].id, {action: "open_dialog_box"}, function(response) {});
});

instead of using chrome.extension.sendMessage as you currently do.

The chrome.tabs variant sends messages to content scripts, whereas the chrome.extension function sends messages to all other extension components.

小开

@apsillers is correct. Also don't forget to return true in your content-script listener or it might close too early.

chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
console.log(message)
return true
});
小开

Here's an example of a background script that sends a message to the content-script file.

background.js

chrome.tabs.sendMessage(tabs[0].id,"your message");

content-script/content.js

chrome.runtime.onMessage.addListener(function (response, sendResponse) {
console.log(response);
});
小开

My use-case required sending a message to the background script from a webpage. I used chrome.runtime.onMessageExternal to catch this message.

Inside of this listener I was basically forwarding the message over to my content script so it could do its thing, but I could not figure out why my content script onMessage listener wouldn't catch the message.

Turns out by waiting for 1 second before sending the message from the webpage (I was basically doing it on load) I was able to see the message hitting my content script.

小开

The problem with the provided solutions is that they raise other errors (Which break my Google Chrome)

@apsillers solution works but the callback raises errors!

How it should look like

// Background.js

chrome.tabs.query({active: true, currentWindow: true}, function(tabs){
chrome.tabs.sendMessage(tabs[0].id, {action: "open_dialog_box"});
});

Now in Content scripts as provided by @Ronan Ca which builds upon @apsillers solution. It is Not ideal to return since we removed the callback from the background script.

// ContentScripts.js

chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
console.log(message)
// return true <- this and the callback in background.js are what caused a crash in extensions page of my Google chrome
});

The background console won't open If I try to do it with callbacks. (It's that bad of a crash)

小开

This is what worked for me in manifest V3. Send message from background script to content script.

  chrome.tabs.sendMessage(sender.tab.id,"your message")

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