Strange javascript object init?

Question

I recently came across this variable initialization in a WebGL tutorial:

var mouse = { x: 0, y: 0 }, INTERSECTED;

I've never seen this format. I understand it's creating an object with an x and y property, but how is INTERSECTED related to the variable/object?

Thanks!

I believe that INTERSECTED is just being initialized. like var INTERSECTED; — Austin Brunkhorst
– Austin Brunkhorst, Commented Dec 5, 2012 at 0:19
@elclanrs: It's not actually the comma operator. It's just that the var statement uses the same character as a separator. — I Hate Lazy
– I Hate Lazy, Commented Dec 5, 2012 at 0:24
Exactly. That's what the wiki says, it provides the example of separator as well as operator. — elclanrs
– elclanrs, Commented Dec 5, 2012 at 0:25
Thanks all! The answers always simpler than my brain wants to let it be. — rob-gordon
– rob-gordon, Commented Dec 5, 2012 at 0:36

Cameron · Accepted Answer · 2012-12-05 00:19:13Z

9

The line is simply declaring two variables (mouse and INTERSECTED), and initializing mouse to { x: 0, y: 0}.

INTERSECTED is not necessarily related to mouse, though clear code should only declare multiple variables together if they are highly related (even then, many prefer to declare every variable on a separate line).

answered Dec 5, 2012 at 0:19

Cameron

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1 Comment

rob-gordon Over a year ago

They are highly related within the script, I think that is what threw me off. Thanks for your answer!

FrancescoMM · Accepted Answer · 2012-12-05 00:23:04Z

3

I may get it wrong, but I think It is just like

var A=3,B;

Defines A with value 3 and B uninitialized. INTERSECTED is just another var.

answered Dec 5, 2012 at 0:23

FrancescoMM

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Ivan · Accepted Answer · 2012-12-05 00:19:33Z

3

INTERSECTED isn't related to mouse. It's just a one line way of initializing two variables. I'm guessing that INTERSECTED is there so that it is treated as a local variable.

answered Dec 5, 2012 at 0:19

Ivan

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Christophe · Accepted Answer · 2012-12-05 00:40:53Z

0

Just adding my 2 cents: the usual convention is to write them on two separate lines and this certainly avoids any confusion:

var mouse = { x: 0, y: 0 },
    INTERSECTED;

(also note that the convention is to have a four space indent which nicely aligns the variables)

answered Dec 5, 2012 at 0:40

Christophe

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