Sunday, January 29, 2012

get the true type prototype vs constructor?


I wanted to see the real type of [] .



I always thought that i can use the apply method or the constructor .



so i tried :



[].constructor ->(showed me) function Array() { [native code] }



and



[].constructor.constructor ->(showed me) function Function() { [native code] }



and



Object.prototype.toString.apply([]) ->(showed me) "[object Array]"




questions



1) Whom to believe ?



2)why line 2 is different ?

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1 comment:

  1. UserJanuary 29, 2012 at 7:13 PM

    1) Whom to believe ?


    All of them. They're all correct


    2) why line 2 is different ?


    Because [].constructor is a function, and the .constructor of a function is the Function constructor.

    The last line is giving you the internal [[Class]] property of the object. It is only accessible by setting the object as the context of the generic toString() method, which is only available on Object.prototype.

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