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doc.open() to get a reference to the document)onload handler for the iframe's document (by writing <body onload="..."> into the iframe.Now what has me stumped is that the global (window) and document objects inside the onload handler (while it's running) is different from the same objects run through JavaScript added via script nodes.
<!doctype html> <html> <head> <script> (function(){ var dom,doc,where,iframe; iframe = document.createElement('iframe'); iframe.src="javascript:false"; where = document.getElementsByTagName('script')[0]; where.parentNode.insertBefore(iframe, where); doc = iframe.contentWindow.document; var _doc = document; doc.open()._l=function() { // the window object should be the one that doc is inside window.vanishing_global=new Date().getTime(); var js = this.createElement("script"); js.src = 'test-vanishing-global.js?' + window.vanishing_global; window.name="foobar"; this.foobar="foobar:" + Math.random(); document.foobar="barfoo:" + Math.random(); // `this` should be the document object, but it's not console.log("this == document: %s", this == document); console.log("this == doc: %s", this == doc); // the next two lines added based on @Ian's comment below console.log("_doc == document: %s", _doc == document); console.log("_doc == doc: %s", _doc == doc); console.log("name: " + window.name + "\n" + "window.vanishing_global: " + window.vanishing_global + "\ntypeof window.vanishing_global: " + typeof window.vanishing_global + "\ndocument.foobar: " + document.foobar); this.body.appendChild(js); }; doc.write('<body onload="document._l();"></body>'); doc.close(); })(); </script> </head> <body> </body> </html> test-vanishing-global.js:console.log("name: " + window.name + "\n" + "window.vanishing_global: " + window.vanishing_global + "\ntypeof window.vanishing_global: " + typeof window.vanishing_global + "\ndocument.foobar: " + document.foobar); Put these two files into a directory, and open the HTML in a browser (tested in latest Chrome and Firefox, same result in both).
this == document: false this == doc: true _doc == document: true _doc == doc: false name: foobar window.vanishing_global: 1366037771608 typeof window.vanishing_global: number document.foobar: barfoo:0.9013048021588475 name: window.vanishing_global: undefined typeof window.vanishing_global: undefined document.foobar: foobar:0.5015988759696484 The this object inside the handler should be either the document object. It is a document object, but not the same document object as the document that it runs inside (it's also not the same as the parent document). The window object inside the handler is also not the same as the window object that runs in JavaScript loaded in the page.
Does anyone know what's going on, and how I can either get a reference to the actual window object, or at least declare and reference global variable from the same global context?
There are no cross-domain issues with this iframe since they're on the same domain. There is an issue if someone sets document.domain, but that's not being done in this example code.
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If you want to do stuff to the iframe 's, use iframe || iframe. contentWindow to access its window , and iframe. contentDocument || iframe. contentWindow.
The Window. parent property is a reference to the parent of the current window or subframe. If a window does not have a parent, its parent property is a reference to itself.
You're declaring everything in the parent page. So the references to window and document are to the parent page's. If you want to do stuff to the iframe's, use iframe || iframe.contentWindow to access its window, and iframe.contentDocument || iframe.contentWindow.document to access its document.
There's a word for what's happening, possibly "lexical scope": What is lexical scope?
The only context of a scope is this. And in your example, the owner of the method is doc, which is the iframe's document. Other than that, anything that's accessed in this function that uses known objects are the parent's (if not declared in the function). It would be a different story if the function were declared in a different place, but it's declared in the parent page.
This is how I would write it:
(function () { var dom, win, doc, where, iframe; iframe = document.createElement('iframe'); iframe.src = "javascript:false"; where = document.getElementsByTagName('script')[0]; where.parentNode.insertBefore(iframe, where); win = iframe.contentWindow || iframe; doc = iframe.contentDocument || iframe.contentWindow.document; doc.open(); doc._l = (function (w, d) { return function () { w.vanishing_global = new Date().getTime(); var js = d.createElement("script"); js.src = 'test-vanishing-global.js?' + w.vanishing_global; w.name = "foobar"; d.foobar = "foobar:" + Math.random(); d.foobar = "barfoo:" + Math.random(); d.body.appendChild(js); }; })(win, doc); doc.write('<body onload="document._l();"></body>'); doc.close(); })(); The aliasing of win and doc as w and d aren't necessary, it just might make it less confusing because of the misunderstanding of scopes. This way, they are parameters and you have to reference them to access the iframe's stuff. If you want to access the parent's, you still use window and document.
I'm not sure what the implications are of adding methods to a document (doc in this case), but it might make more sense to set the _l method on win. That way, things can be run without a prefix...such as <body onload="_l();"></body>
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