Feedback: irt.org FAQ Knowledge Base Q879

Feedback on: irt.org FAQ Knowledge Base Q879

Sent by Scott Smith on July 27, 2000 at 13:31:58: - feedback #1546

Length:
Just right

Comments:
Good routine for cloning objects, but I think it contains a typo. "typeof i" should be "typeof what[i]", e.g.

function cloneObject(what)
{
for (i in what)
{
if (typeof what[i] == 'object')
this[i] = new cloneObject(what[i]);
else
this[i] = what[i];
}
}

Sent by Compin Philippe on August 30, 2000 at 09:42:19: - feedback #1686

Worth:
Worth reading

Comments:
this :
if (typeof i == 'object') {
doesn't work to copy objects recursively...
this:
if (typeof what[i] == 'object') {
should work better.

Sent by Maurice Lynch on October 18, 2000 at 10:00:10: - feedback #1879

Worth:
Very worth reading

Comments:
Thanks for the code for cloning objects however when trying to copy a Form object in IE5.5 I get a "class not registered" error. Any ideas?

<html>
<head>
<script language="JavaScript">
function cloneObject(what) {
for (i in what) {
this[i] = what[i];
}
}
function copyForm() {
myform = new cloneObject(document.forms[0]);
alert(myform.elements[0].value);
}
</script>
</head>
<body>
<form>
<input type="text" value = "Hello">
<input type="button" value="Copy Form" onClick="copyForm()";>
</form>
</body>
</html>

Sent by Philip Chalmers on August 07, 2002 at 17:14:01: - feedback #4060

Worth:
Worth reading

Length:
Too short

Technical:
Not technical enough

Comments:
This is OK provided the object is not part of a hierarchy with both parent and child pointers. If it is part of such a hierarchy, you get a recursive lop and the browser runs out of stack space.

So I do't think there is a general solution to this problem. At the very minimum you have to know which properties are parent pointers and avoid making them new cloneObjects. But that may also fail if you delete the try to restore a whole sub-tree of a hierarchy, because some of the saved parent pointers will now point to nothing.