53925 - Self-overwriting JavaScript works until M17, broken in M18

Status: VERIFIED WONTFIX

(Core :: DOM: Core & HTML, defect, P3)

Description

[Bob Kanefsky]

To reproduce:  Open the attached test case and press the button.

If the test passes, the variables remain accessible throughout

the execution of the function that is overwriting its own page.



Netscape 4.75:           Fails

IE 5.0 (2022, Mac):      Passes



Mozilla M15 2000041805:  Passes

Mozilla M17 2000080712:  Passes

Mozilla M18 2000082310:  Fails

Mozilla M18 2000091509:  Fails

Mozilla M18 2000092220:  Fails

Comment 1

[Bob Kanefsky]

Attachment: Test case

Comment 2

[Jesse Ruderman]

Same results on windows 98 for 2000 092408.  all/all

Comment 3

[Phil Schwartau]

Here is a core JavaScript version of the testcase (no HTML) : 


var var1 = " seem ";
var var2 = "passes the test.";


rewrite_page();


function rewrite_page () {
  print("This test was failed by Mozilla 2000092220 and  this browser"); 
  print(", it would  " +  var1 + ', ');
  print(var2);
}


As long as we call the function rewrite_page() after the definition of
var1 and var2, the test passes. The output is:  


     This test was failed by Mozilla 2000092220 and  this browser
     , it would   seem ,
     passes the test. 


If we put the call to rewrite_page() before the definition of var1 and var2,
the test fails: 


     This test was failed by Mozilla 2000092220 and  this browser
     , it would  undefined,
     undefined


I don't see any JavaScript Engine problem here; reassigning to DOM Level 0 
for a look. In the reporter's testcase, the calls to "print" I have used above
are calls to "document.write" instead -

Comment 4

[Bob Kanefsky]

Attachment: Triple test case showing it works only before document is loaded.

Comment 5

[Bob Kanefsky]

The above test case shows:
  1.  During script loading, the rewrite works.
  2.  After script loading, via a setTimeout, it fails.
  3.  From a form's event handler, it fails.

Comment 6

[Bob Kanefsky]

Attachment: onLoad test case

Comment 7

[Johnny Stenback (:jst)]

The "problem" here is that document.open() ends up calling JS_ClearScope() which
basically ends up removing non-standard properties on the global object (the
'window'). While this might seem a bit weird, it is intentional and mozilla
currently behaves the same way 4.x does. IOW, WONTFIX, there are easy
workarounds for this problem that do work in both 4.x, IE and mozilla, for
instance one could copy the value of the global variables into local variables
before calling document.open() and then use the local variables from then on... 

Comment 8

[Fabian Guisset]

VERIFIED wontfix