How should I connect my pages to search and highlight text on current tab?
Currently I have:
manifest.json does defining content/backgr/event page do significant things,auto inject code etc?
popup.html essentially a shell for the search input which is used by search.js
search.js should this be in background/event/content/popup.html page?
What I still don't understand after reading:
What is a content page vs. background/event page?
I know one is constantly running vs injected, but that's as much as I got from the chrome extension manual, I still don't quite understand if the content script/page is seperate from the popup.html for example and what the difference between a script in the popup.html vs content page/script is.
What I know:
I know how to search for text on a page, and replace it or change its style etc. using JS.
I need to read up on the messaging API for Chrome Extensions.
I know I need to know how to use the messaging API, is it going to be required for page search and highlighting?
Summary:
I don't need a walk through or full answer, just a little help visualizing how Chrome extensions work, or at minimum how I should set mine up in relation to page interaction IE:
search.js content page injected >>>>> popup.html
and maybe a short bit about how injection works in chrome extensions(IE, do I only need to specify that it is content page in manifest.json to have it injected or is there more work to it)/expected behavior?
Apologies for the jumbled thoughts/question/possibly missing the things relevant to my questions while reading the manual.
I will start with making the purpose of each kind of page/script more clear.
First is the background page/script. The background script is where your extension lives. It isn't required, but in order to do most extension things, you need one. In it you can set up various event listeners and such depending on what you want it to do. It lives in its own little world and can only interact with other pages and scripts using the chrome.* apis. If you set it up as an event page it works exactly the same except that it unloads when not in use and loads back into memory when it has something to do.
Content scripts refer to injected Javascript and/or css. They are the primary tool used for interacting with web pages. They have very limited access to chrome.* apis, but they have full access to the DOM of the page they are injected into. We will come back to using them in a minute.
Now for Popup pages. Unlike the background script and content script, popups have both a HTML and JS portion. The HTML part is just like any other page, just small and as a overlay popup coming out from the icon. The script portion of it, however, can do all the things the background page does, except that it unloads whenever the popup is closed.
Now that the distinctions are more clear let's move on to what you want to do. It sounds like you want to open the popup, have the user enter text to search for in the current tab, then highlight that text on the page. Since you said that you already know how you plan on highlighting the text, I will leave that part to you.
First to set up our manifest file. For this particular action, we don't need a background script. What we do need is both the "tabs" and "activeTab" permissions. These will enable us to inject our script later. We also need to define the browser action with it's popup. Altogether it would look something like this:
"browser_action": {
"default_icon": "icon.png",
"default_popup": "popup.html"
},
"permissions": [
"tabs", "activeTab"
]
Now in our popup.html file, we can only have markup and css, no inline code at all. We will put it all in our js file and include it. Something like this should work:
<!DOCTYPE html>
<html>
<head>
<script src="popup.js"></script>
</head>
<body>
<input type="text" id="searchText">
<button id="searchButton">Search</button>
</body>
</html>
This is where we come back to the content script stuff. There are two ways to inject a content script, first is to define it in the manifest. This works best when you always want to inject it for a particular set of url's. Second, to use the chrome.tabs.executeScript method to inject it when we need to. That is what we will use.
window.onload = function(){
document.getElementById('searchButton').onclick = searchText;
};
function searchText(){
var search = document.getElementById('searchText').value;
if(search){
chrome.tabs.query({active:true,currentWindow:true},function(tabs){
chrome.tabs.executeScript(tabs[0].id,{file:search.js});
chrome.tabs.sendMessage(tabs[0].id,{method:'search',searchText:search});
});
}
}
With this, we have successfully injected our script and then send the search text to that script. Just make sure that the script is wrapped in a onMessage listener like this:
chrome.runtime.onMessage.addListener(function(message,sender,sendResponse){
// message.searchText is the text that was captured in the popup
// Search/Highlight code goes here
});
And that pretty much sums it up. With that, you should be able to get it working. If something is still not clear let me know and I will fix it.
I think what's confusing you is the non-existant concept of a "content page". There is no such thing. What you're likely referring to is a "content script". Let me explain the three main components of an extension:
Background Page
As you said, this is the persistent aspect of a Chrome Extension. Even though it can be HTML page it is never rendered. You simply use it to run JavaScript and other content that stays persistent. The only way to "refresh" the background page is to refresh the extension in the extension manager, or to re-install the extension.
This is most useful for saving information that should remain persistent, such as authentication credentials, or counters that should build up over time. Only use the background page when absolutely necessary, though, because it consumes resources as long as the user is running your extension.
You can add a background script like to manafest file like this:
"background": {
"scripts": [
"background.js"
]
},
Or like this:
"background": {
"page": "background.html"
},
Then simply add background.js to background.html via a typical tag.
Popup
This is what you see when you click the icon on the toolbar. It's simply a popup window with some HTML. It can contain HTML, JavaScript, CSS, and whatever you would put in a normal web page.
Not all extension need a popup window, but many do. For example, your highlight extension may not need a popup if all it's doing is highlighting text on a page. However, if you need to collect a search result (which seems likely) or provide the user with some settings or other UI then a popup is a good way to go about this.
You can add a popup to the manifest file like this:
"browser_action": {
"default_popup": "popup.html"
},
Content script
As I mentioned, this is not a "page" per se -- it a script, or set of scripts. A content script is what you use to infuse JavaScript into pages the user is browser. For example, a user goes to Facebook and a content script could change the background to red. This is almost certainly what you'll need to use to highlight text on a page. Simply infuse some JavaScript and any necessarily libraries to search the page or crawl the dom, and render changes to that page.
You can inject content scripts every time a user opens any URL like this:
"content_scripts": [
{
"matches" : [
"<all_urls>"
],
"js" : [
"content.js"
]
}
],
The above injects "content.js" into "all urls".
You'll also need to add this to the permissions:
"permissions": [
"<all_urls>",
]
You can even add JQuery to the list of content scripts. The nice thing about extensions is that the content scripts are sandboxed, so the version of JQuery you inject will not collide with JQuery on pages the user visits.
Related
In my chrome extension I want to have a background script for obvious reasons. However I now also want to have a background page in which I like right here discribed load some html (Chrome extension: loading a hidden page (without iframe)) using an iFrame which I can interact with using a content script. But when I'm trying to load both the background script and the background page like so:
...
"background":{
"scripts": ["background_script.js"]
},
"background": {
"page": "iFrameBackground.html",
"persistent": true
},
...
and then try to send a message from my content script to the background script I get this error:
Unchecked runtime.lastError: Could not establish connection. Receiving end does not exist.
So either I'm missing something entirely here or are you really just able to use one of the two?
Thank you :)
Problems
Only one declaration method can be used.
Your json is invalid as it has two identical keys so Chrome won't even install it.
Solution
Choose just one method. Any method.
You can access DOM in your background script/page regardless of the way it's declared.
The result of each method is identical: they both create a background page. An extension can have just one background page where any amount of background scripts are loaded - just like in any other web page. The scripts method exists just for convenience: it simply generates a dummy HTML page as you can see in devtools inspector for the background page.
I play card games on a board game platform called BoardGameArena.
Now I'd like to have a card tracker-helper that would inform me about the remaining cards for one of the games called "Papayoo". The entire log is available while playing the game so should be a pretty straightforward Chrome extension, right?
All of the relevant action happens on the right side of the page:
<div id="right-side-second-part">
<div id='logs_wrap'>
<div id='logs'>
<div id='seemorelogs'><a id='seemorelogs_btn'href='#' onclick='return false'></a></div>
</div>
</div>
</div>
It's a bit weird that I see an empty template like above if I do "View Page Source" of "Save Page As", but the <div id='logs_wrap'> is being populated during the game, and I can see the entries appear using the "Inspect" functionality. But maybe that's expected for the fields that are being populated dynamically (I'm not a web developer).
Anyway, here is my hello world attempt for a Chrome extension:
manifest.json
{
"name":"Papayoo Helper",
"description":"Papayoo game helper for the BGA platform",
"version":"1",
"manifest_version":2,
"content_scripts": [
{
"matches": ["http://boardgamearena.com/*/papayoo*"],
"js": ["tracker.js"]
}
]
}
an example URL of the game is https://boardgamearena.com/7/papayoo?table=122356466 so I assume it should be matched by my rule.
tracker.js
document.getElementById("right-side-second-part").innerHtml = "<div id='tracker'>Hello world!</div>" + this.innerHtml;
and it should prepend my "Hello world!" to the existing element.
I load the extension by visiting chrome://extensions/ and selecting "Load unpacked".
It doesn't work as nothing is displayed, which leads to the following questions:
How to debug the behavior and see why it doesn't get loaded?
How to adjust it to update automatically (or at least frequently)?
I guess the logic will be simply to iterate elements within <div id='logs'> once the extension itself is working.
Thanks!
matches
It should be https not http
This is a Single Page Application site which doesn't reload pages from server when you navigate so you need to run the content script on the entire site and then watch for the changed URL path explicitly in your code.
It should also include the subdomains like en so we'll add *. to match both the main site and its subdomains.
To detect the change in URL see this answer
Result:
"matches": ["https://*.boardgamearena.com/*"]
innerHtml
innerHtml should be innerHTML
Don't assign innerHTML of another site using = or += as it removes all the event listeners attached from JavaScript thus breaking its functionality. Instead use insertAdjacentHTML or explicitly build DOM via document.createElement or some js library.
To debug, use the built-in devtools, there are many tutorials. First make sure the content scripts are listed in devtools UI (in this case they won't be for reasons explained above) then set a breakpoint in the code somewhere and reload the tab, see what happens when it triggers.
To repeatedly do something you can use timers e.g. setInterval and setTimeout. Another approach is to use MutationObserver to react to site's changes.
What I have so far:
manifest.json
{
"name": "Append Test Text",
"description": "Add test123 to body",
"version": "1.0",
"permissions": [
"activeTab"
],
"background": {
"scripts": ["background.js"],
"persistent": false
},
"browser_action": {
"default_title": "Append Test Text"
},
"manifest_version": 2,
"permissions": [
"https://*/*",
"http://*/*",
"tabs"
]
}
background.js
chrome.browserAction.onClicked.addListener(function(tab) {
chrome.tabs.executeScript({
code: 'var div=document.createElement("div"); document.body.appendChild(div); div.innerText="test123";'
});
});
What it does:
Upon clicking the chrome extension icon, it adds <div>test123</div> to the <body></body> of any given page.
What I Would Like To Achieve:
Alike the bit.ly Chrome extension, I would like to append a lot of content to the DOM. Upon clicking on the extension icon, I would like an overlay element to be added tot he <body></body> along with a sidebar where I can add jQuery tab switches.
As you can see, I've just taken this picture whilst creating this question for StackOverflow.
Questions:
Regarding my current progress and/or any scripts you may submit with your answer; How can I give this appended element an ID and/or class name and check whether this is already present on the DOM before adding it over and over again upon clicking the icon.
How can I append a lot of content to the page to reside within my sidebar. jQuery is present within the site I am creating this extension to be used on. Am I able to create a standard HTML file which is then fetched and then programmatic injected into the DOM which I can use jQuery scripts on for the likes of switching tabs (not Chrome tabs, tabs within the injected content).
Why not take a look at how bit.ly extension does it?
Looking at the code, bit.ly appends a fixed position, 100% width/height iframe to the page that contains an "app" page from the package. Clicking again removes the iframe. There's a bit of special code to work with frameset pages (which I won't comment on here), but other than that that's the general idea.
Part of the page is half-transparent, which gives the illusion of a sidebar, but it does indeed cover the whole page. This is the easiest way to do it, since otherwise you risk breaking the page's layout and there is no general "magic" solution that works everywhere to have your content side by side.
// Injection
var iframe = document.createElement("iframe");
iframe.id = "my-awesome-extension-iframe";
iframe.style.width = "100%";
/* ..more styling like that.. */
iframe.src = chrome.runtime.getURL('my_ui.html');
document.body.appendChild(iframe);
// Removal
var iframe = document.getElementById("my-awesome-extension-iframe");
if (iframe) {
iframe.parentNode.removeChild(iframe);
}
To have full control over the looks of your UI, injecting a frame is preferable, as the page's own CSS and scripts won't "bleed" into your context. Whatever libraries you want, you can include there as you would in a normal page.
If you vehemently object to the idea of using a frame, you can try and inject your UI directly into the page - but beware interfering/incompatible code, restrictive CSP and CSS that bleeds through. This question is relevant: How to really isolate stylesheets in the Google Chrome extension?
You could make the above snippets as separate files, and use executeScript with the file attribute to inject them. They do not require any libraries like jQuery.
Note that code in that frame will have the same level of privilege as content script code - if you need APIs unavailable in content scripts, you'll need to message the background to do it. You'll also need to list the page itself, and all of its resources, in web_accessible_resources.
Dynamic DOM elements may be the way to go if you are adding simple user controls inside a layout. However, if you want to inject a full layout it can be a pain. jQuery may come handy with its function load.
You could have the layout of your sidebar in a static HTML file and have it loaded with jQuery in a given container. Something like this should do it, assuming an id="myContainer":
jQuery
$('#myContainer').load('layout.html')
To answer the first question, to give a specific ID to a dynamically created element, you only have to treat it like a DOM element and set an id to it.
JavaScript
var myElement = document.createElement('div');
myElement.id = 'myContainer';
myElement.className = 'kitten-background jumbo button';
// ...
// other properties you may need
// ...
document.body.appendChild(myElement);
For the second question, to check if an element exists you may as well use jQuery again. If a selector matches something, its length attribute will be greater than zero so that's a clean validation to check that $('#myContainer').length == 0 before inserting.
Good luck in what you are trying to achieve and have fun!
First of all, all the answers will be much appriciated, as I'm running out of my own ideas.
I have a "simple" problem to tackle. I wanna do a chrome extension, which would basically track the websites you're visiting (with content included). To clarify, we have full consent of the users to do this. :-)
What I did so far, isn't working well (I've tried to use many of the hooks provided by chrome API, ie chrome.webNavigation.onCommitted, chrome.webRequest.onBeforeRequest, chrome.webNavigation.onCompleted, chrome.webRequest.onBeforeRedirect, chrome.history.onVisited).
The best option so far is to use chrome.history.onVisited, but then again, I've no idea how to get website content from it - I've tried to execute content script which returns document.documentElement.outerHTML, but in order to do so I need to know tabId, which isn't available there.
Basically, something is messed up in chrome API or my thinking - probably the latter :)
I want to point out, that it almost works, but not on all cases. It's hard for me to debug which cases fail though.
Thanks a lot for all the tips I can get!
Based on your clarification in a comment I could suggest you to use content scripts and message passing.
At the moment when the user press "start recording" button you can - from the background page - execute content script which will intersect content of the pages already opened and then will send it back to the background page for further processing (save possibly). You can query for all tabs in any window using chrome.tabs.query function:
chrome.tabs.query({}, function(tabs){
console.log(tabs); //tabs array contain all tabs in all windows.
});
Iterating over this array you can execute script in all tabs using it's tab.id:
tabs.forEach(function(tab){
chrome.tabs.executeScript(tab.id, { 'file': 'cs.js' })
});
Then you can attach event handler to listen up for changes in tabs:
chrome.tabs.onUpdated.addListener(function(change){
if(change.status === 'complete'){
//inject content script
}
});
Second scenario is to add content script to every page user visits adding proper manifest entry:
...
"content_scripts": [
{
"matches": ["<all_urls>"],
"js": ["cs.js"]
}
],
...
After cs.js load you can call background page and ask it if the extension should capture page content (using messaging passing). If yes - do the same as above, if not, just do nothing.
It is the easiest and most convenient way of doing what you need.
I'm building my first Chrome extension. I've gone through Chrome developer documentation, but I couldn't comprehend few topics.
What I've understood:
There are two actions:
Browser action (button outside address bar)
page action (button inside address bar)
For both actions we have background pages:
Background pages can be background.html or background.js for browser actions
Or background.html or eventPage.js for page actions
I am using a page action. For default popup page I used popup.html.
Now where does this background.html and eventPage.js fit in (especially background.html, as I already have my popup.html, do I need that?)
What should eventPage.js have? What should background.html have?
In your manifest.json, if you're using an "event page" (recommended to reduce your extension's memory use) you'll have something like
{
...
"background": {
"scripts": ["eventPage.js"],
"page": "eventPage.html"
"persistent": false
},
...
}
Now, the above manifest won't actually work: you can only have one of the "scripts" or "page" key in the "background" dictionary. The simplest thing to do is define "scripts". Then you can write a bunch of javascript, and have it run in response to various events like chrome.runtime.onMessage and chrome.pageAction.onClicked.
The javascript you list in the "scripts" key runs in the context of an HTML document and can use DOM APIs like document.createElement() while it's running. By default, Chrome will generate a document of the form:
<html>
<head></head>
<body>
<script src="event.js"></script>
</body>
</html>
to hold the scripts you list. You'll see this in chrome://extensions/ if you click on the "background page" link next to "Inspect views". However, sometimes you might want that document to have more elements pre-defined. I've seen examples like:
<html>
<head></head>
<body>
<script src="event.js"></script>
<canvas width="300" height="400" id="the_canvas"></canvas>
</body>
</html>
so event.js can use document.getElementById('the_canvas') to retrieve a canvas it can draw on. Without the custom document, your javascript could still run:
var canvas = document.createElement('canvas');
canvas.width = 300;
canvas.height = 400;
and get the same result, but the document can be easier. That HTML file is what you'd put in the background.page key in your manifest.
As #SirDemon mentioned, you can sometimes get away with no background/event page at all, if you put everything into a browser action's popup. Because a page action is supposed to only appear for pages it's relevant to, you'll usually need a background/event page to control the page action.
You do not necessarily need a background page or background script. If you intend to create an extension that does not require any human interaction, then you would need them.
Page and browser actions usually mean you intend to have some sort of UI, so no need for background stuff. Just add your scripts etc to your main 'default_popup' html page as you would normally.