變量提升

變量聲明提升 Vs. 函數聲明提升 1. 變量聲明提升       先看以下代碼： 1）var in_window = "a" in window; console.log(in_window);  2）var in_window = "a" in window; console.log(in_window); if(!("a" in window)) { var a = 1; } 3）var a

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