What's the Secret Behind jQuery's `(function(window, undefined){})(window)` Encapsulation?

Unveiling the Mystery of jQuery's Encapsulation: Deciphering (function( window, undefined ) { })(window)

The jQuery library's unique encapsulation technique, as seen in the prologue, has generated curiosity among developers. Delving into its syntax, we seek to demystify the enigmatic variables and their purpose.

What's 'undefined' Doing?

The undefined variable, contrary to its name, holds no significance beyond its default state. By creating a local variable labeled undefined, jQuery ensures that any global variable of the same name is inconsequential within its scope. Thus, jQuery can operate independently without potential conflicts.

Why Pass and Repass 'window'?

The window variable serves a special purpose in the context of encapsulation. Introducing it as a local variable streamlines performance by reducing JavaScript's scope search. When looking up variables, JavaScript prioritizes local variables, which are faster to locate compared to global ones. Localizing window enables quicker access and enhances execution efficiency.

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