I am working with Chrome extension's content script to create a complex display that is added on web pages.
I have first tested it directly integrated on a website, but now I need to put it in an extension.
The thing is that the content script API for Chrome only allows to inject javascript. That means that, to inject complex HTML layouts I would need to write it entirely with JS objects, which is long to write, hard to maintain and absolutely not designer-friendly.
I'm wondering if anyone know or can think of a clever way to get a better workflow on this.
It's relatively easy to add whole web pages by having your content script inject them in an iframe. Just follow these guidelines:
Place the *.htm
or *.html
files in your extension's source folder(s).
Place any *.css
and *.js
files, that the HTML uses, in the extension folder(s) too.
Declare the HTML file(s) as resources. EG:
"web_accessible_resources": ["Embedded_Hello_world.htm"]
Do not use any inline, or external server, javascript in your HTML files. This avoids problems with the Content Security Policy (CSP).
This question doesn't cover communicating with the page/iframe, but if you want to do that, it is a bit more involved. Search here on SO; it's been covered many times.
Example:
You can see this in action by:
- Creating a new extension folder.
- Download jQuery into it.
- Create the 5 files as specified below.
- Load the unpacked extension (You can see similar steps in this answer.)
- Reload this page in Chrome; you'll see the "Hello World" page, embedded at the top.
Create these files in the extension folder:
manifest.json:
{
"manifest_version": 2,
"content_scripts": [ {
"js": [ "iframeInjector.js" ],
"matches": [ "https://stackoverflow.com/questions/*"
]
} ],
"description": "Inject a complete, premade web page",
"name": "Inject whole web page",
"version": "1",
"web_accessible_resources": ["Embedded_Hello_world.htm"]
}
iframeInjector.js:
var iFrame = document.createElement ("iframe");
iFrame.src = chrome.extension.getURL ("Embedded_Hello_world.htm");
document.body.insertBefore (iFrame, document.body.firstChild);
Embedded_Hello_world.htm:
<!DOCTYPE html>
<html><head>
<title>Embedded Hello World</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="HelloWorld.css" rel="stylesheet" type="text/css">
<script type="text/javascript" src="jquery.min.js"></script>
<script type="text/javascript" src="HelloWorld.js"></script>
</head><body>
<p>Hello World!</p>
</body></html>
HelloWorld.css:
body {
color: red;
background-color: lightgreen;
}
HelloWorld.js:
$(document).ready (jQueryMain);
function jQueryMain () {
$("body").append ('<p>Added by jQuery</p>');
}
I had the same issue, that my extension heavily relies on script templates
Here's what I did:
- create
templates.html
to store script templates in
- add
templates.html
to the web_accessible_resources
as in the the above answer^^
- access
templates.html
from content.js
with xhr and parse with jQuery
manifest.json
"web_accessible_resources": ["templates.html"]
templates.html
<script id="template1" type="text/template">
<div class="template1">template1</div>
</script>
<script id="template2" type="text/template">
<div class="template2">template2</div>
</script>
content.js
function getTemplates(){
return new Promise(function(resolve){
$.ajax({
url: chrome.extension.getURL('/templates.html'),
success: function(data) {
var $templates = $('<div></div>').append($.parseHTML(data)).find('script'),
templates = {};
$templates.each(function(){
templates[this.id] = this.innerHTML;
});
return resolve(templates);
}
});
});
}
getTemplates().then(function(templates){
console.log(templates.template1); //<div class="template1">template1</div>
});
This may be better, no external library and no iframe. Is nearly the same as iautomation solution.
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
var div = document.createElement('div');
div.innerHTML = this.responseText;
document.body.insertBefore(div, document.body.firstChild);
} else {
console.log('files not found');
}
};
xhttp.open("GET", chrome.extension.getURL("/content.htm"), true);
xhttp.send();