每个调用都会计算JavaScript属性吗？

由于length是JavaScript属性,因此我是否使用是否重要

for( var i = 0; i < myArray.length; i++ )

要么

var myArrayLength = myArray.length;
for( var i = 0; i < myArrayLength ; i++ )

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for(var i = 0, iLen = myArray.length; i < iLen; i++)

有关各种Javascript循环结构的基准测试,请参阅http://blogs.oracle.com/greimer/resource/loop-test.html.