1 2 3 4 5 (function() { var a = b = 5; })(); console.log(b); console.log(a); 上面的输出结果: A: 5，5 B: undefined，undefined C: 5，undefined D: 5，UncaughtReferenceError:aisnotdefined
1 2 3 4 5 (function() { var a = b = 5; })(); console.log(b); console.log(a); 上面的输出结果: A: 5，5 B: undefined，undefined C: 5，undefined D: 5，UncaughtReferenceError:aisnotdefined
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