541026 - including chrome://browser/content/utilityOverlay.js throws exceptions

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[Jesse Andrews]

User-Agent:       Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6
Build Identifier: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6

Error console reports:

Error: missing ; before statement
Source File: chrome://browser/content/utilityOverlay.js
Line: 219, Column: 4
Source Code:
    let browser = w.getBrowser(); 

Whenever you try to use utilityOverlay.js

Reproducible: Always

Steps to Reproduce:
1. open the error console: Tools -> Error Console
2. clear all current errors
3. add utilityOverlay.js

src=document.createElement('script'); window.document.body.appendChild(src); src.setAttribute('src', 'chrome://browser/content/utilityOverlay.js');

Actual Results:  
Error: missing ; before statement
Source File: chrome://browser/content/utilityOverlay.js
Line: 219, Column: 4
Source Code:
    let browser = w.getBrowser(); 

Expected Results:  
It should be able to use load utilityOverlay.js without error.

My extension taboo uses utilityOverlay to be able to call openUILinkIn to open a new link in the proper location based on the users preferences (obtained via whereToOpenLink)

It seems like this breakage could break many extensions in FF 3.6

Comment 1

[Jesse Andrews]

type="application/x-javascript;version=1.7" fixes this.

Perhaps the bug is that there should be a list of files that now require a specific version of JS?

Comment 2

[Tanner M. Young [:tmyoung]]

I get the same error, except my error (on trunk) says

Error: missing ; before statement
Source File: chrome://browser/content/utilityOverlay.js
Line: 149, Column: 4
Source Code:
    let params = arguments[2]; 

This line was added in http://hg.mozilla.org/mozilla-central/rev/f53d65371670

The line in the error for this original report was added by http://hg.mozilla.org/releases/mozilla-1.9.2/rev/7f9ef4bef487

It seems to be caused by using let instead of var.

I'll also post a testcase.

Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.3a1pre) Gecko/20100120 Minefield/3.7a1pre (.NET CLR 3.5.30729) ID:20100120043108

Comment 3

[Tanner M. Young [:tmyoung]]

Attachment: Testcase that loads the script

This testcase loads the script using the method in the report.

Also, this may have something to do with Bug 522858, but I'm not totally sure.

Comment 4

[Dão Gottwald [:dao]]

(In reply to comment #1)
> type="application/x-javascript;version=1.7" fixes this.
> 
> Perhaps the bug is that there should be a list of files that now require a
> specific version of JS?

You should always specify the latest version when loading a chrome script from a content page.

Comment 5

[Jesse Andrews]

> You should always specify the latest version when loading a chrome script from
> a content page.

If we should always specify it, why not make it default?

I've been reading these pages for years and this was never recommended:

https://developer.mozilla.org/en/Firefox_3.6_for_developers
https://developer.mozilla.org/en/Firefox_3.5_for_developers
https://developer.mozilla.org/en/Firefox_3.0_for_developers
https://developer.mozilla.org/En/Updating_extensions_for_Firefox_3.6
https://developer.mozilla.org/En/Updating_extensions_for_Firefox_3.5
https://developer.mozilla.org/En/Updating_extensions_for_Firefox_3.0

So I'm not how we should have known.  

Either FF3.6 versions of libraries is more strict about specifying versions, or the libraries changed.  There has been NO communication about this and as a result we are spending many hours trying to figure out WTF is wrong with our code.

The only page I can find that says anything about using version in our extensions is on the FAQ which states we should use 1.7 not the latest (currently 1.8.2): https://developer.mozilla.org/en/Extension_Frequently_Asked_Questions

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So while this issue might be minor to you, it isn't to the thousands of extension authors who have wasted hours trying to fix their extensions.