Chrome extension: Communication between content script and background.html
I am new to Chrome extensions. I am trying to communicate between the content script and the background.html page. The background.html sends a request, "hello", to the content script and the content script should respond back with "hello background" alert. But it's just not happening. My background.html code is:
function testRequest() {
chrome.tabs.getSelected(null, function(tab) {
chrome.tabs.sendRequest(tab.id, {greeting: "hello"});
});
}
content.js code:
chrome.extension.onMessage.addListener(
function(request, sender, sendResponse) {
if (request.greeting == "hello")
alert("hello background");
}
);
popup.html code:
<!doctype html>
<html>
<head></head>
<body>
<form>
<input type="button" value="sendMessage" onclick="testRequest()" />
</form>
</body>
</html>
manifest.json:
{
"browser_action": {
"default_icon": "icon.png",
"popup": "popup.html"
},
"background": {
"page": "background.html"
},
"permissions": [
"tabs",
"http://*/*",
"https://*/*",
"notifications",
"contextMenus"
],
"content_scripts": [
{
"matches": ["http://*/*","https://*/*"],
"js": ["content.js"]
}
],
"name": "FirstExtension",
"version": "1.0"
}
Please help!
Answer
sendRequest/onRequest is replaced with sendMessage/onMessage in Chrome 20. *Message is not just an alias for *Request, it's a different API.
If you want to support Chrome <20 (many Ubuntu users are still at Chromium 18, because the PPA is not updated), use onRequest and sendRequest. Otherwise, use the *Message methods.
Another problem is that your function is located in the background page, and the call is made in the pop-up. These are different scopes, if you want to call a background page method from the popup, use chrome.extension.getBackgroundPage():
chrome.extension.getBackgroundPage().testRequest();
Final note: You're using manifest version 1 and inline event handlers. This practice is deprecated, for more information, see http://code.google.com/chrome/extensions/manifestVersion.html.