212581 - Array splice() function not truncating array when deleting

Status: RESOLVED WORKSFORME

(Rhino Graveyard :: Core, defect)

Description

[Steven Gutz]

User-Agent:       Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
Build Identifier: 

The Array class splice() function doesn't always truncate the array when 
removing an element.  For example:

myArray.splice( 27, 1 );

The correct element is removed, but the last element in the array appears 
twice rather then shortening the array by one element.



Reproducible: Always

Steps to Reproduce:
1.
2.
3.

Comment 1

[Phil Schwartau]

cc'ing Igor, but I can't reproduce the bug with the following example:

$ java org.mozilla.javascript.tools.shell.Main
Rhino 1.5 release 5 0000 00 00
js>
js> arr = [];
js> for (var i=0; i<31; i++) {arr[i] = i;}
js> arr
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30
js> arr.length
31

js> var removed = arr.splice(27,1)
js> removed
27
js> arr
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,28,29,30
js> arr.length
30


Steven: can you give the complete test you are using? 
And what version of Rhino are you using? Thanks -

Comment 2

[Steven Gutz]

I can't give you the exact code because it is buried within a proprietary 
application, but I have an array or strings created from code similar to the 
following:

var myArray = new Array();
myString = "string1,string2,string3,string4,string5";
myArray = myString.split( "," );
myArray.sort();
.
.
.
lengthb4 = myArray.length;
myArray.splice( 2, 0 );
lengthAfter = myArray.length;

At this point the desired item has been deleted from the array, but the array 
length is still that same (lengthB4 == lengthAfter), and the last element is 
now duplicated.  Though sometimes it seems to work properly (it seems to 
depend on which element gets deleted)

To work around the problem I create a new Array and copy all but the last 
element to (assuming the array length before and after the splice is the same).

I can't give you much more help than that - maybe if I have time I'll trace 
through the Rhino code myself to see if I can track it down for you.  It Rhino 
1.5R4_1 BTW.

Comment 3

[Phil Schwartau]

Your original report mentioned |myArray.splice( 27, 1 )|.
The above comment mentions |myArray.splice(2, 0)|.

There is a big difference between 1 and 0 as the second parameter!
Don't have time to look this up in the spec right now, but here is
the syntax for splice() from 

http://devedge.netscape.com/library/manuals/2000/javascript/1.5/reference/array.html


---
SYNTAX
splice(index, howMany, [element1][, ..., elementN])


PARAMETERS

index
Index at which to start changing the array.

howMany
An integer indicating the number of old array elements to remove.
If howMany is 0, no elements are removed. In this case, you should
specify at least one new element.   

element1, ..., elementN
The elements to add to the array. If you don't specify any elements,
splice simply removes elements from the array.
---


Note in particular the line

> If howMany is 0, no elements are removed. In this case, you should
> specify at least one new element.   


Is what you are seeing inconsistent with this specification?

Comment 4

[Steven Gutz]

Sorry, it should actually be a 1 not a 0

myArray.splice( 2, 1 );

Comment 5

[Igor Bukanov]

Can not reproduce the bug. 

Steven, please reopen it if you have a reproducible standalone example or any
other information that can help to find out why splice did not work for you.

Comment 6

[Igor Bukanov]

Trageting as resolved against 1.5R5

Comment 7

[Youri Andropov]

Sorry but even with Rhino 1.7R4, this (serious) bug is not fixed !

Ex:
var tab = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29];
var l = tab.length;
var r = Math.floor(Math.random() * l);

var val = tab.splice(r, 1);

my tab becomes [0,1,2,3,4,5,6,7,8,9,10,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,29]