javascript函数中变量的范围

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javascript函数中变量的范围

Java代码

1.   
   
2. var first = 'hi there';   
   
3. var first = (function() {   
   
4.     console.log("first", first); // undefined   
   
5.     var first = "hello world";   
   
6. })();   
   
7. //相当于   
   
8. var first = 'hi there';   
   
9. var first = (function() {   
   
10.     var first;//the variable declaration moved to the top   
    
11.     console.log("first", first); // undefined   
    
12.     var first = "hello world";   
    
13. })();   
    
14.   
    
15. // second test case   
    
16. var second = 'hi there';   
    
17. var second = (function() {   
    
18.     console.log("second", second ); // "hi there"   
    
19.     // here, we DO NOT declare a local "second" variable   
    
20. })();   
    
21.   
    
22. // in the second test case, we don't declare the local variable, so the console.log call refers to the global variable and the value is not "undefined"   
    
23. //link:http://jsfiddle.net/pomeh/ynqBs/  

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