How delete works in JavaScript.

[dmjpro]

Here is a code snippet i tried out.

[code=javascript]
var array = new Array(12,20,"De basis Jana");
alert(array.len gth);
delete array.length;
alert(array.len gth);
[/code]

Basically first i tried to delete the array then i did this to delete a property.
It's not working, before this what i tried ....

[code=javascript]
var o = new MyClass();
for(i in o) if(o.hasOwnProp erty(i)) alert(i);
delete o.prop1;
for(i in o) if(o.hasOwnProp erty(i)) alert(i);
[/code]

It's working, now my question is that how delete works in JavaScript?
Basically JavaScript engine uses a garbage collector then why delete comes in?
One more thing if i do ...

[code=javascript]
delete o.prop1;
o.prop1 = null;
[/code]

what do these two mean?
I gone a mess. :-)

[rnd me]

you typically can't delete native props like length.

delete remove a property from an object. setting a property to null does just that: the object's property exists, it's value set to null.

delete is useful for controlling inheritance, cleaning up data for presentation and archiving, and to a lessor extent, clearing memory.

think of an object as folder whose files are the properties. setting something to null would be like a 0 byte file; it's still there, still shows up in the file explorer. deleting it would remove the file from the folder or the property from the object.