Reading Content Globals: Difference between revisions
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Described here is a straightforward and reliable way to read values from the content page's global scope. | Described here is a straightforward and reliable way to read values from the content page's global scope. | ||
It relies on asynchronously [https://developer.mozilla.org/en/DOM/window.postMessage passing messages] via events (available in Firefox 3.0 and higher), and [https://developer.mozilla.org/en/Using_native_JSON native JSON support] (available in Firefox 3.5 and higher). | It relies on asynchronously [https://developer.mozilla.org/en/DOM/window.postMessage passing messages] via events (available in Firefox 3.0 and higher), and [https://developer.mozilla.org/en/Using_native_JSON native JSON support] (available in Firefox 3.5 and higher). | ||
See the snippet at userscripts.org: http://userscripts.org/scripts/show/85398 | |||
== Example == | == Example == | ||
Revision as of 15:49, 4 September 2010
Described here is a straightforward and reliable way to read values from the content page's global scope. It relies on asynchronously passing messages via events (available in Firefox 3.0 and higher), and native JSON support (available in Firefox 3.5 and higher).
See the snippet at userscripts.org: http://userscripts.org/scripts/show/85398
Example
This script:
// ==UserScript==
// @name Global Reader
// @include *
// @require http://userscripts.org/scripts/source/85398.user.js
// ==/UserScript==
function got(name, value) {
console.log('got global named', name, 'with value', value);
}
read_content_global('secret1', got);
read_content_global('secret2', got);
Run on a page like:
<html> <head> <script type="text/javascript"> var secret1 = 42; var secret2 = 17; </script> </head> <body> Page with globally scoped javascript values. </body> </html>
The console will display:
got global named secret1 with value 42 got global named secret2 with value 17
