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62

Javascript Variables as Object Pointers

rated 0 times [ 66] [ 4] / answers: 1 / hits: 16478 / 11 Years ago, fri, july 26, 2013, 12:00:00

I have a question out of curiosity. So I looked into how JS handles variable assignment and I get it. How does variable assignment work in JavaScript?

But the same principle doesn't seem to exhibit itself in the following code I am working on:

var temp = playlist1[0];

playlist1[0] = playlist1[1];

playlist1[1] = temp;

I know this is a standard way to swap array elements. But if temp is pointing at playlist1[0], and playlist1[0]'s contents are changed to playlist1[1]'s then how come I don't end up with two playlist1[1] values in a row?

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answered 11 Years ago aliah · Accepted Answer

Not only variables are object pointers. All values (that are not primitives) are object pointers. So temp is an object pointer. playlist1 is a object pointer to an array object whose elements are object pointers. e.g. playlist1[0] is an object pointer, playlist1[1] is an object pointer, etc.

But if temp is pointing at playlist1[0]

This doesn't make sense. temp is an object pointer. It points to an object. playlist1[0] is not an object; it's an object pointer. temp = playlist1[0]; makes the object pointer temp point to the same object as object pointer playlist1[0].

If you know C, it is equivalent to something like this:

Object *playlist1[10];



Object *temp = playlist1[0];

playlist1[0] = playlist1[1];

playlist1[1] = temp;