Question

Possible Duplicate:
What does var x = x || {} ;

I have this lines in js, it is simple i am sure but i am not sure what the last part does – (xin || {})

var xin = (function (name) {return name;}(xin || {}));

as I understand it, xin is a object constructor so now I can create object of xin. Just not too sure what the xin || {} does. Can someone enlighten me please, thanks

Answer 1

xin || {}

is the same as:

xin ? xin : {};

or, in longer form:

if(xin) {
    return xin;
}
else {
    return {};
}

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EDIT: See linked duplicate question. jAndy puts it nicely:

|| is the logical OR.

The expression

var x = x OR {};

should become more obvious then.

If x has a falsy value (like null, undefined, 0, ""), we assign x an empty object {}, otherwise just keep the current value. The long version of this would look like

var x = x ? x : {};