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| Described here is a straightforward and reliable way to read values from the content page's global scope.
| | The technique [http://wiki.greasespot.net/index.php?title=Reading_Content_Globals&oldid=5610 previously described] at this page is no longer necessary. |
| 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).
| | Read [[Content Script Injection]] for an easier replacement technique. |
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| See the snippet at userscripts.org: http://userscripts.org/scripts/show/85398
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| == Example ==
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| This script:
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| <pre>
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| // ==UserScript==
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| // @name Global Reader
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| // @include *
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| // @require http://userscripts.org/scripts/source/85398.user.js
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| // ==/UserScript==
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| function got(name, value) {
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| console.log('got global named', name, 'with value', value);
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| }
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| read_content_global('secret1', got);
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| read_content_global('secret2', got);
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| </pre>
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| Run on a page like:
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| <pre>
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| <html>
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| <head>
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| <script type="text/javascript">
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| var secret1 = 42;
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| var secret2 = 17;
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| </script>
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| </head>
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| <body>
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| Page with globally scoped javascript values.
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| </body>
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| </html>
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| </pre>
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| The console will display:
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| <pre>
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| got global named secret1 with value 42
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| got global named secret2 with value 17
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| </pre>
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| [[Category:Coding Tips:Interacting With The Page]] | | [[Category:Coding Tips:Interacting With The Page]] |
| [[Category:@require Library]]
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The technique previously described at this page is no longer necessary.
Read Content Script Injection for an easier replacement technique.
