I have a chrome extension with a popup page which passes a boolean variable to my content page via simple one-time requests. The content page would then do some action based on the status of the boolean variable passed from the popup page. This was working perfectly until I accidentally removed the extension (still in developer mode, the extension is unpacked) and had to re-load it.
This caused an extension context invalidated error to appear in the popup inspection console and the webpage console seems to validate that the popup page and content script are not communicating. The webpage with the chrome extension active shows this error: Unchecked runtime.lastError: The message port closed before a response was received.
Based on a few answers I've already seen, it seems that reloading my chrome extension has "orphaned" my original working content script from the rest of my extension, which causes the aforementioned "Unchecked runtime.lastError: The message port closed before a response was received." error on the webpage console.
I believe that I cannot just reinject my content script again as my content script has DOM event listeners. Is there a possible way to remove the currently running orphan script? Or is there any suggested workaround to this problem?
Here is my popup.js:
chrome.tabs.query({'active': true, 'currentWindow': true}, function (tabs) {
chrome.tabs.sendMessage(tabs[0].id, {cTabSettings: (some boolean variable)});
});
Here is my content.js:
// Listening for message from popup.js
chrome.runtime.onMessage.addListener(
function(request, sender, sendResponse) {
if (request.cTabSettings === true) {
enabled = true;
} else if (request.cTabSettings === false) {
enabled = false;
}
});
// DOM listener and action
document.addEventListener('mousemove', function (e) {
// Some action
chrome.runtime.sendMessage({sender: "content", selText : "blah"}, function () {
console.log("success");
});
}, false);
I am using chrome developer mode version 76. Just to rephrase, this chrome extension was working (content script communicates with popup) before I accidentally reloaded it.
Since the orphaned content script can still receive DOM messages, send one from your new working content script to the ghosted content script via window, for example. Upon receiving the message you'll unregister all listeners (and nullify any global variables) which will also make your old script eligible for automatic garbage collection.
content.js:
var orphanMessageId = chrome.runtime.id + 'orphanCheck';
window.dispatchEvent(new Event(orphanMessageId));
window.addEventListener(orphanMessageId, unregisterOrphan);
// register all listeners with named functions to preserve their object reference
chrome.runtime.onMessage.addListener(onMessage);
document.addEventListener('mousemove', onMouseMove);
// the popup script checks it to see if a usable instance of content script is running
window.running = true;
function unregisterOrphan() {
if (chrome.runtime.id) {
// someone tried to kick us out but we're not orphaned!
return;
}
window.removeEventListener(orphanMessageId, unregisterOrphan);
document.removeEventListener('mousemove', onMouseMove);
try {
// 'try' is needed to avoid an exception being thrown in some cases
chrome.runtime.onMessage.removeListener(onMessage);
} catch (e) {}
return true;
});
function onMessage(msg, sender, sendResponse) {
//...........
}
function onMouseMove(event) {
// DOM events still fire in the orphaned content script after the extension
// was disabled/removed and before it's re-enabled or re-installed
if (unregisterOrphan()) { return }
//...........
}
popup.js should ensure a content script is injected before sending a message:
async function sendMessage(data) {
const [tab] = await chrome.tabs.query({active: true, currentWindow: true});
if (await ensureContentScript(tab.id)) {
return await chrome.tabs.sendMessage(tab.id, data);
}
}
async function ensureContentScript(tabId) {
try {
const [{result}] = await chrome.scripting.executeScript({
target: {tabId},
func: () => window.running === true,
});
if (!result) {
await chrome.scripting.executeScript({
target: {tabId},
files: ['content.js'],
});
}
return true;
} catch (e) {}
}
Please check this answer
It's not about removal of script but to avoiding error in case.
Related
I'm writing an extension to demonstrate the use of messages. Here's the idea.
There is an HTML page with a mytext text field and a popup page that also contains a mytext field.
Both text fields are always synchronized in content.
Direct messages between the popup page and the content page do not work. Therefore, all communication takes place through an intermediary - the background page.
Messages are passed between the popup page and the background page via port.postMessage. The background page and content page communicate via chrome.runtime.sendMessage and chrome.tabs.sendMessage.
background.js
let popup_port;
debugger;
chrome.extension.onConnect.addListener(function (port)
{
popup_port = port;
popup_port.onMessage.addListener(function (msg)
{
chrome.tabs.query(
{
currentWindow: true,
active: true
},
function (tabs)
{
// This is where the error occurs.
chrome.tabs.sendMessage(tabs [0].id, msg);
});
return true;
});
});
chrome.runtime.onMessage.addListener(function (msg)
{
popup_port.postMessage(msg);
});
content.js
debugger;
chrome.runtime.onMessage.addListener(function (msg)
{
if (msg.query)
chrome.runtime.sendMessage(mytext.value);
else
mytext.value = msg.input;
});
popup.js
let port = chrome.extension.connect({name: '...'});
debugger;
port.postMessage({query: true});
port.onMessage.addListener(function (textMsg)
{
mytext.value = textMsg;
});
function postMyMessage ()
{
port.postMessage({input: mytext.value});
}
mytext.oninput = postMyMessage;
When I open a popup window, everything works correctly - the text from the main page also appears in the field of the popup page.
But when I enter text into the field from the popup page, an error occurs in the background page:
TypeError: Cannot read property 'id' of undefined
When I tested my code while writing this post, it (suddenly!!!) worked correctly - when I enter text in the popup, it appears in the main page as well. What was it !?
You say that it is possible to directly establish a connection between the popup page and the content page. How to do it right?
I placed this in the popup.js file:
let port = chrome.extension.connect({name: 'abc'});
debugger;
port.postMessage('hello');
while in content.js:
chrome.extension.onConnect.addListener(function (port)
{
port.onMessage.addListener(function (msg)
{
alert(msg);
});
});
As a result an error occurs:
Could not establish connection. Receiving end does not exist.
What is the correct way to organize two-way communication between popup.js and other parts of the extension (content.js)?
When a user clicks the browser icon, spiderSimulator() should run.
I can get it to work – once.
Like, I’ll click the icon and it does what it’s supposed to. But if I refresh the page and click it a second time, it doesn’t work. if I go to another site and try again, it doesn’t work.
If I update the extension, refresh the page, and clear the cache, it works again – sometimes. it’s super inconsistent.
Any idea what’s going wrong here?
content.js
// Adds an event listener to the browser icon to sends a message to background.js.
chrome.runtime.onMessage.addListener(
function (request, sender, sendResponse) {
if (request.message === "clicked_browser_action") {
console.log( 'send message' );
chrome.runtime.sendMessage({"message": "spider_simulator"});
}
}
);
background.js
// Called when the user clicks on the browser action.
chrome.browserAction.onClicked.addListener(function (tab) {
// Send a message to the active tab
chrome.tabs.query({active: true, currentWindow: true}, function (tabs) {
var activeTab = tabs[0];
console.log('browser action');
chrome.tabs.sendMessage(activeTab.id, {"message": "clicked_browser_action"});
});
});
chrome.runtime.onMessage.addListener(
function (request, sender, sendResponse) {
if (request.message === "spider_simulator") {
console.log('run the spider');
spiderSimulator()
}
}
);
// removes the site's stylesheet and replaces it with my own;
// turns all page elements into nested list items.
function spiderSimulator() {
console.log( 'inject stylesheet' );
chrome.tabs.insertCSS({
file: 'search-spider-simulator.css'
});
console.log( 'execute script' );
chrome.tabs.executeScript({
file: 'search-spider-simulator.js'
});
window.close();
}
As mentioned by wOxxOm, window.close() executed in the background page acts on itself - essentially terminating the background portion of your extension.
Not sure what was meant there; if you need to close the tab you're talking to, then this also needs to be executeScript'ed.
I have created a chrome extension to enable clipboard data access. The solution is explained in details here Implementing 'Paste' in custom context menu. Now the problem is how to port this extension to Edge. There is a tool for that I know I used it, and maybe it is working, but my problem is how to "consume" this extension, what is equivalent to chrome.runtime.sendMessage in Edge? In Chrome I used this https://developer.chrome.com/apps/messaging#external-webpage - the part 'Sending messages from webpages', but in Edge I just can't find anything similar. Thanks for your time and help.
There is runtime.sendMessage() in Edge too.
https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/runtime/sendMessage
The thing to keep in mind is that the runtime object is defined on the browser object, not chrome.
Sends a single message to event listeners within your extension or a different extension.
If sending to your extension, omit the extensionId argument. The runtime.onMessage event will be fired in each page in your extension, except for the frame that called runtime.sendMessage.
If sending to a different extension, include the extensionId argument set to the other extension's ID. runtime.onMessageExternal will be fired in the other extension.
Extensions cannot send messages to content scripts using this method. To send messages to content scripts, use tabs.sendMessage.
This is an asynchronous function that returns a Promise.
I managed to solve this. There is no way (at least I couldn't find it) to communicate from web page with extension background script (and only the background script can get data from the clipboard and has the 'browser' object defined). So what I did, I communicated with content script and content script communicated with background script. Here is the code.
PAGE CODE:
contextMenuPaste: function () {
if (getBrowserName() == 'EDGE') {
window.postMessage({
direction: "from-page-script"
}, "*");
}
},
window.addEventListener("message", function (event) {
if (event.source == window &&
event.data.direction &&
event.data.direction == "from-content-script") {
console.log('Data in page script', event.data.message);
}
});
CONTENT SCRIPT CODE
window.addEventListener("message", (event) => {
// If message came from page-script send request to background script to get clipboard data
if (event.source == window &&
event.data &&
event.data.direction == "from-page-script") {
browser.runtime.sendMessage({
message: "getClipboardData"
},
function(clipboardData) {
messagePageScript(clipboardData);
}
);
}
});
// Send clipboard data to page script
function messagePageScript(clipboardData) {
window.postMessage({
direction: "from-content-script",
message: clipboardData
}, "*");
}
BACKGROUND SCRIPT CODE
browser.runtime.onMessage.addListener(
function(req, sender, callback) {
if (req) {
if (req.message) {
if (req.message == "installed") {
console.log('Checking is extension is installed!');
callback(true);
}
else if(req.message = "getClipboardData") {
console.log('Get clipboard data');
callback(getDataFromClipboard());
}
}
}
return true;
}
);
function getDataFromClipboard() {
var bg = browser.extension.getBackgroundPage();
var helperTextArea = bg.document.getElementById('sandbox');
if (helperTextArea == null) {
helperTextArea = bg.document.createElement("textarea");
document.body.appendChild(helperTextArea);
}
helperTextArea.value = '';
helperTextArea.select();
// Clipboard data
var clipboardData = '';
bg.document.execCommand("Paste");
clipboardData = helperTextArea.value;
helperTextArea.value = '';
return clipboardData;
}
But there is one tiny issue. This code works if I have a break-point set on line
bg.document.execCommand("Paste");
and it doesn't if I don't have that break-point. I thought it is a trimming issue, added pauses, delayed executions but nothing helped. I will start a new question for that issues and will copy solution here (if I find one).
So, I am trying to do something like parental control. When I start my extension for the first time it works fine, but when I use it again elements don't hide, whole page loads and then it redirects, I want to hide all elements on page and then redirect, I am not using onBeforeRequest I want to use it with google search too and I don't know if I can put regex inside urls option. My manifest is ok, I start content script at "document_start".
background.js
var activeTabUrl;
var regex = /http:\/\/www.youporn.com\//
chrome.tabs.onUpdated.addListener(function (tabId, changeInfo, tab) {
chrome.tabs.query({
active: true,
currentWindow: true
}, function (arrayOfTabs) {
activeTabUrl = arrayOfTabs[0].url;
});
if (activeTabUrl.match(regex)) {
chrome.tabs.update({
url: "http://google.com/"
})
} else {
chrome.tabs.sendMessage(tabId, {
action: "show_my_page"
}, function (response) {});
}
});
myscript.js (content_script)
_ini();
function _ini() {
document.getElementsByTagName("html")[0].style.display = "none";
chrome.extension.onMessage.addListener(function (msg, sender, sendResponse) {
if (msg.action == 'show_my_page') {
document.getElementsByTagName("html")[0].style.display = "block";
}
});
}
That's a wrong approach, but first why it fails.
If you're executing at document_start, then the only node existing in the dom would be the document node. Not even html yet.
Yes, you could potentially wait for html node to appear, but this is very roundabout. Your goal is to prevent navigation in the first place - and for blocker-style functionality there's the webrequest API (which, IIRC, was specifically implemented for AdBlock).
Here's a minimal sample from the docs themselves:
chrome.webRequest.onBeforeRequest.addListener(
function(details) { return {cancel: true}; },
{urls: ["*://www.evil.com/*"]},
["blocking"]);
You can also redirect that with a redirectUrl instead of cancel in the blocking response. See also CatBlock for a complete sample.
I would like to use a Chrome Extension to download the current page's DOM. I'm not sure why, but when my download occurs, the result is just a text file with either 'null' or 'undefined', rather than the DOM. I've tried to assimilate the knowledge from here and here, but I can't seem to get the message from content.js through to popup.js.
Additionally, I'm not sure why this actually works. When I read the docs, it seems like I need to send the message from popup.js to content.js by selecting the active tab:
chrome.tabs.query({currentWindow: true, active: true}, function(tabs) {
chrome.tabs.sendMessage(tabs[0].id, {message: 'getMessageFromContent'}, function(response) {
//Code to handle response from content.js
}
});
My current code:
content.js
var page_html = DOMtoString(document);
chrome.runtime.sendMessage({method: 'downloadPageDOM', pageDOM: thisPage});
function DOMtoString(document_root) { ... }
background.js
chrome.tabs.query({currentWindow: true, active: true}, function(tab) {
var page_html;
chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
if (request.message == 'downloadPageDOM')
page_html = request.pageDOM;
else if (request.message == 'getPageDOM')
sendResponse(page_html);
});
});
popup.js
document.addEventListener('DOMContentLoaded', function() {
var download_button = document.getElementById('download_button');
download_button.addEventListener('click', function() {
chrome.runtime.sendMessage({message:'getPageDOM'}, function(response) {
download(response, "download.html", "text/html");
});
});
});
function download(data, fileName, mimeType) { ... }
I feel like I'm missing a crucial understanding of how message passing works. If anyone could take a second to help me understand why the file that downloads just has 'null', I would sincerely appreciate it.
You're over-complicating this, which leads to a lot of logical errors.
You've set up the background page to act like a message proxy, and the content script itself triggers updating your page_html variable. Then the popup pulls that data with another message.
Note that page_html will not contain the current tab's data in any case: you're overwriting this data with the last loaded tab.
What you can do is completely cut out the middleman (i.e. background.js). I guess you got confused by the fact that sending a message TO a popup is a generally a bad idea (no guarantee it's open), but the other way around is usually safe (and you can make it always safe).
Solution 1 (bad, but here for educational purposes)
The logic of your app is: once the user clicks the button, make the snapshot at that moment. So, instead of making your content script do its work immediately, add a message listener:
// content.js
chrome.runtime.onMessage(function(message, sender, sendResponse) {
else if (request.message == 'getPageDOM')
sendResponse(DOMtoString(document));
});
function DOMtoString(document_root) { ... }
And in your popup, request it:
// popup.js
// (Inside the click listener)
chrome.tabs.query({currentWindow: true, active: true}, function(tabs) {
// Note that sending a message to a content script is different
chrome.tabs.sendMessage(tabs[0].id, {message:'getPageDOM'}, function(response) {
download(response, "download.html", "text/html");
});
});
However, this solution is not 100% robust. It will fail if the content script is not injected into the page (and this can happen). But it's possible to fix this.
Solution 2
Let's not assume the content script is injected. In fact, most of the time you don't NEED to inject it automatically, only when the user clicks your button.
So, remove the content script from the manifest, make sure you have host permissions ("<all_urls>" works well, though consider activeTab permission), and the use programmatic injection.
There is a little-used form of programmatic injection that collects the value of the last executed statement. We're going to use that.
// content.js
DOMtoString(document); // This will be the last executed statement
function DOMtoString(document_root) { ... }
In the popup, execute script, collect results:
// popup.js
// (Inside the click listener)
chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
chrome.tabs.executeScript(tabs[0].id, {file: "content.js"}, function(data) {
// Data is an array of values, in case it was executed in multiple tabs/frames
download(data[0], "download.html", "text/html");
});
});
NOTE: All of the above assumes that your function DOMtoString actually works.