关于javascript：为什么用`var`定义的匿名函数可以在全局范围内调用？

Why can anonymous functions defined with `var` be called in global scope?

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function setupSomeGlobals() {
// Local variable that ends up within closure
var num = 666;
// Store some references to functions as global variables
var gAlertNumber = function() { console.log(num); }
}

setupSomeGlobals();

gAlertNumber(); //works, WHY?!!

console.log(num); //does not work, GOOD

我希望galertNumber()不能在setupSomeGlobals()函数之外工作…