actionscript-3 - 在AS3中在循环中或循环前声明变量？

Question

我应该在循环之前声明 _mcContainer var 还是不声明？ (性能提升？)

for(var i:uint = _startIndex; i <= _endIndex; ++i){    
    var _mcContainer:MovieClip = _mcParent["i_" + _position];
}

或

var _mcContainer:MovieClip;
for(var i:uint = _startIndex; i <= _endIndex; ++i){
    _mcContainer = _mcParent["i_" + _position];
}

？

Answer 1

测试并不难...

...但是根据文档，它应该没有任何区别，因为变量声明无论如何都会被提升到方法 block 的顶部。

来自the docs :

An interesting implication of the lack of block-level scope is that you can read or write to a variable before it is declared, as long as it is declared before the function ends. This is because of a technique called hoisting , which means that the compiler moves all variable declarations to the top of the function.