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[RESOLVED] namespace pattern

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Jan 04.2015

Hi everyone!

I am getting deeper in the namespace pattern in JavaScript, and have come across this code patter several times:

[code]

var myApp = function (namespace, undefined)
{
namespace = namespace || {} ;
//do stuff…

return namespace;
}(myApp);

[/code]

It is passing ‘undefined’ as the second parameter.

What is the purpose of ‘undefined’ as the second parameter in the function??

Thank you very much!

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JavaScript

2 Comments(s) ↴

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@Jeff_MottJan 04.2015 — There are a couple purposes.

One is to ensure that undefined is truly undefined. Anywhere, in any script, some silly person could write [FONT=Courier New]undefined = 're-define undefined cause im evil';[/FONT]. But within the scope of your function, since the second parameter is named "undefined" and no second argument is passed in, then within that function, "undefined" is guaranteed to be undefined.

A second is to aid minifiers. The global undefined can be minified down to [FONT=Courier New]void 0[/FONT], but we can go smaller. Function parameters are like local variables. Minifiers can rename them down to a single letter without affecting behavior.
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@hebrerilloauthorJan 04.2015 — Thank you very much Jeff!! Now it is clear for me.

All the best
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