Basic google chrome extension message passing not working - javascript

I've been trying to get message passing for a chrome extension to work but console.log(response) gives me undefined. I've looked at the docs for message passing and on stackoverflow, but in my case it won't work. I am at a loss as to why.
myscript.js:
chrome.extension.sendRequest({greeting: "hello"}, function(response) {
console.log(response);
return true;
});
background.js:
chrome.runtime.onMessage.addListener(
function(request, sender, sendResponse) {
sendResponse({farewell: "goodbye"});
return true;
});
manifest.json
{
"manifest_version": 2,
"name": "nameasf",
"description": "asfasaf",
"version": "1.0",
"permissions": [
"tabs",
"http://somedomain.com/"
],
"content_scripts": [
{
"matches": ["http://somedomain.com/*"],
"css": ["mystyles.css"],
"js": ["jquery.js", "myscript.js"],
"all_frames": true
}
],
"background": {
"scripts": ["background.js"]
},
"browser_action": {
"default_icon": "icon.png",
"default_popup": "popup.html"
}
}

You are using the obsolete chrome.extension.sendRequest.
Use chrome.runtime.sendMessage instead.
(Note: You are already using the new chrome.runtime.onMessage so you don't have to change anything on the listener side.)
A couple of sidenotes:
For the code presented here you don't need any permission (especially not the powerful tabs permission).
And it is a good idea to use non-persistent background pages (a.k.a. event-pages) whenever possible as they are considerably more resource-friendly.

Related

Error on calling Javascript APIs within Firefox extension

I am currently building a web extension and in the stage of porting between browsers. On moving from Chrome to Firefox I am coming against an issue in using the runtime.sendMessage API that allows me to talk between the content and background scripts.
The message code in the content script:
browser.runtime.sendMessage('d089938d-ba63-4c40-98ab-b8515db1bbca', { greeting: "screenshot-please" }, function (response) {
localStorage.setItem("image", response.farewell);
});
var image = localStorage.getItem("image");
The Background script:
var img = saved-image;
browser.runtime.onMessage.addListener(
function (request, sender, sendResponse) {
if(request.greeting === "screenshot-please"){
sendResponse({
farewell: img
});
}
}
);
and the manifest:
{
"description": "...",
"manifest_version": 2,
"name": "...",
"permissions": [
"find",
"tabs",
"activeTab",
"<all_urls>"
],
"applications": {
"gecko": {
"id": "..."
}
},
"background": {
"scripts": ["/JavaScript/moz-initialPopup.js"]
},
"content_scripts": [
{
"all_frames": true,
"matches": ["*://127.0.0.1:3000/*"],
"js": ["Javascript/dataGrab.js"]
}
],
"icons": {
"48": "..."
},
"browser_action": {
"browser_style": true,
"default_title": "...",
"default_icon": {
"48": "..."
}
},
"version": "1.0"
}
When in chrome (replace all instances of *browser with *chrome) this messaging system works fine. When in firefox, in the developer tools I get 'ReferenceError: browser is not defined'.
Can anyone assist me in why I would not be able to access the browser here?

Chrome Extension - Notification on Certain Web Pages

I'm looking to pop up a chrome notification whenever the user visits certain web pages e.g. 'www.amazon.com' or 'google.com' etc. The extension loads into chrome perfectly fine with no errors, but the notification doesn't pop up when I head to those specific pages.
I currently have the below scripts.
manifest.json
{
"name": "Test",
"version": "0.0.1",
"manifest_version": 2,
"description": "This extension was created with the awesome extensionizr.com",
"homepage_url": "http://www.test.co.uk",
"icons": {
"16": "icons/icon16.png",
"48": "icons/icon48.png",
"128": "icons/icon128.png"
},
"default_locale": "en",
"background": {
"page": "src/bg/background.html",
"persistent": true
},
"options_page": "src/options/index.html",
"browser_action": {
"default_icon": "icons/icon19.png",
"default_title": "browser action demo",
"default_popup": "src/browser_action/browser_action.html"
},
"permissions": ["notifications"],
"content_scripts": [
{
"matches": ["http://www.amazon.com/*", "http://amazon.co.uk/*"],
"js": ["js/script.js"]
}
]
}
js/script.js
if(onCertainWebsitesNeedNotificationAppearTrue) {
// send message to background script
chrome.runtime.sendMessage({greeting: "hello"}, function(response) {
});
}
background.js
chrome.extension.onMessage.addListener(
function(request, sender, sendResponse) {
chrome.pageAction.show(sender.tab.id);
sendResponse();
});
chrome.runtime.onMessage.addListener(
function(request, sender, sendResponse) {
//alert("good");
if (request.greeting == "hello")
createNotification();
});
function createNotification(){
var opt = {type: "basic",title: "Your Title",message: "Your message",iconUrl: "128.png"}
chrome.notifications.create("notificationName",opt,function(){});
//include this line if you want to clear the notification after 5 seconds
setTimeout(function(){chrome.notifications.clear("notificationName",function(){});},10000);
}
New to chrome extension coding so any help would be appreciated!
onCertainWebsitesNeedNotificationAppearTrue isn't defined anywhere so the code is not executed and the message is not sent.
Use the devtools debugger to diagnose the problems.
Also move the code from chrome.extension.onMessage callback inside chrome.runtime.onMessage callback and remove the former.

Very simple Chrome Extension to display alert

I am trying to create a quick Chrome extension (complete beginner) and just want to display an alert whenever the icon is clicked, so I tried the following:
manifest.json
{
"name": "Something",
"version": "1.0",
"manifest_version": 2,
"description": "Woohoo",
"browser_action": {
"default_icon": "icon.png"
},
"content_scripts" : [{
"matches": ["<all_urls>"],
"js" : ["bgscript.js"]
}]
}
bgscript.js
chrome.browserAction.onClicked.addListener(function(tab) {
alert('icon clicked')
});
However when I click on my icon, nothing happens! Looking at the above - can anyone spot why this wouldn't work?
In order to be notified for browser-action's onClicked event, you need a background-page (or better yet event-page), not a content-script.
Change your manifest like this:
// Replace that:
"content_scripts" : [{...}]
// with this:
"background": {
"persistent": false,
"scripts": ["bgscript.js"]
}
If you want the browser-action to invoke something on a content-script, you need to communicate throught the background-page using Message Passing (e.g. Simple one-time requests).
E.g.:
manifest.json
{
"name": "Something",
"version": "1.0",
"manifest_version": 2,
"description": "Woohoo",
"browser_action": {
"default_icon": "icon.png"
},
"background": {
"persistent": false,
"scripts": ["background.js"]
},
"content_scripts" : [{
"matches": ["<all_urls>"],
"js" : ["content.js"]
}]
}
background.js
chrome.browserAction.onClicked.addListener(function (tab) {
/* Send a message to the active tab's content script */
chrome.tabs.sendMessage(tab.id, { action: 'saySomething' });
});
content.js
chrome.runtime.onMessage.addListener(function (msg) {
/* We received a message, let's do as instructed */
if (msg.action === 'saySomething') {
alert('something');
}
});

How can I call functions defined in a Chrome Extension from regular websites?

I'd like to make a website that is not part of the chrome plugin but rather just uses some API that the plugin exposes to it. Is this possible and if so, how do I do it? I googled this question and was unable to find anything.
I'm trying to use content scripts but nothing happens. Can someone explain what's wrong here?
manifest.json
{
"manifest_version": 2,
"name": "Hello World Extension",
"description": "This extension prints hello world.",
"version": "1.0",
"background": {
"page": "background.html"
},
"browser_action": {
"default_icon": "img/icon.png",
"default_popup": "popup.html"
},
"content_scripts": [
{
"matches": ["http://locahost:8888/*"],
"js": ["EmotivAPI.js"]
}
]
}
EmotivAPI.js
var port = chrome.runtime.connect();
console.log("Hello?");
window.addEventListener("message", function (event) {
// We only accept messages from ourselves
if (event.source != window)
return;
if (event.data.type && (event.data.type == "FROM_PAGE")) {
console.log("Content script received: " + event.data.text);
port.postMessage(event.data.text);
alert("recieved!");
}
}, false);
js in the webpage
window.sayHello = function () {
window.postMessage({ type: "FROM_PAGE", text: "Hello from webpage!" }, "*");
}
console.log('Emotiv extension loaded.');
}
I'm calling window.sayHello() from the console
Content Scripts can help you in this case.
The content script will be injected into a page:
"content_scripts": [
{
"matches": ["http://www.google.com/*"], // try with "http://localhost:*/*" or "http://localhost:*"
"css": ["mystyles.css"],
"js": ["content_script.js"]
}
]
If you want to inject the code only sometimes, use the permissions field instead
/* in manifest.json */
"permissions": [
"tabs", "http://*/*"
],
In you extension html file, you can then execute the script by:
chrome.tabs.executeScript(null, {file: "content_script.js"});

I don't understand Google Chrome extensions. Please help.

I want to do something that seems like it should be fairly simple, but I can't get it to work.
All I want it to do is when the button in the popup is clicked I want to log the word "Hello" to the console. At the moment nothing happens. No error message. Just nothing.
Here is my manifest.jason file
{
"name": "Content Script",
"version": "1.0",
"description": "Experiments with content scripts.",
"permissions": [
"tabs", "http://*/*", "https://*/*"
],
"browser_action": {
"default_icon": "icon.png",
"popup": "popup.html"
}
}
Here is my popup.html
<h1>Hello</h1>
<script>
function changeField() {
chrome.tabs.getSelected(null, function(tab) {
chrome.tabs.sendRequest(tab.id, {"code": "sayHello"});
});
}
</script>
<button onclick="changeField();">Click</button>
Here is my contentscript.js
function sayHello() {
console.log("Hello");
}
chrome.extension.onRequest.addListener(
function(request, sender, response) {
if(request.code == 'sayHello') {
sayHello();
}
}
);
I've been reading the docs but they seem to skip over a lot of things. If someone could explain why this doesn't work I would be eternally grateful.
You didn't inject your content script to the page which console lives in.
Add content_scripts segment to your manifest.json file.
There is a reference of manifest.json file on chrome extension official site.
{
"name": "Content Script",
"version": "1.0",
"description": "Experiments with content scripts.",
"permissions": [
"tabs", "http://*/*", "https://*/*"
],
"browser_action": {
"popup": "popup.html"
},
"content_scripts":[{
"matches":["http://*/*"],
"js":["content_script.js"]
}]
}

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