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Education/Learning/ModifyBrowser: Difference between revisions
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Education/Learning/ModifyBrowser (view source)
Revision as of 16:34, 19 February 2009
, 19 February 2009→Second Attempt
| Line 174: | Line 174: | ||
Clearly this code has some problems, since we've completely broken addTab. Let's look for clues in the '''Error Console''' (Tools > Error Console). Notice the following exception appear whenever we try to add a new tab: | Clearly this code has some problems, since we've completely broken addTab. Let's look for clues in the '''Error Console''' (Tools > Error Console). Notice the following exception appear whenever we try to add a new tab: | ||
Error: uncaught exception: [Exception... "Could not convert JavaScript argument" | |||
nsresult: "0x80570009 (NS_ERROR_XPC_BAD_CONVERT_JS)" location: "JS frame :: | |||
chrome://global/content/bindings/tabbrowser.xml :: addTab :: line 1161" data: no] | |||
Now we know how to find errors our JavaScript produces. Looking back at our code, it's clear that that '''childNodes.length''' is not zero, but 1 by default (i.e., there is always at least one tab, even if it isn't visible). A quick modification to the code, and we get: | Now we know how to find errors our JavaScript produces. Looking back at our code, it's clear that that '''childNodes.length''' is not zero, but 1 by default (i.e., there is always at least one tab, even if it isn't visible). A quick modification to the code, and we get: | ||