非常蛋疼的JavaScript试题

JavaScript有很多地方和我们熟知的C、Java等的编程习惯不同，这些不同会产生很多让人意想不到的事情。前段时间在知乎有人发了写Javascrtip试题，觉得挺好玩的，这里跟大家分享一下。

01

view sourceprint?
1 (function () {    

2     return typeof arguments;    

3 })();    

4    

5 A. "object" 

6 B. "array" 

7 C. "arguments" 

8 D. "undefined" 
答案：A

02

view sourceprint?
1 var f = function g() {  

2         return 23;  

3     };  

4 typeof g();  

5    

6 A. "number" 

7 B. "undefined" 

8 C. "function" 

9 D. Eorror 
答案：D

03

view sourceprint?
1 (function (x) {  

2     delete x;  

3     return x;  

4 })(1);  

5    

6 A. 1  

7 B. null  

8 C. undefined  

9 D. Error 
答案：A

04

view sourceprint?
1 var y = 1,  

2     x = y = typeof x;  

3 x;  

4    

5 A. 1  

6 B. "number" 

7 C. undefined  

8 D. "undefined" 
答案： D

05

view sourceprint?
01 (function f(f) {  

02     return typeof f();  

03 })(function () {  

04     return 1;  

05 });  

06    

07 A. "number" 

08 B. "undefined" 

09 C. "function" 

10 D. Error 
答案：A

06

view sourceprint?
01 var foo = {  

02     bar: function () {  

03         return this.baz;  

04     },  

05     baz: 1  

06 };  

07 (function () {  

08     return typeof arguments[0]();  

09 })(foo.bar);  

10    

11 A. "undefined" 

12 B. "object" 

13 C. "number" 

14 D. "function" 
答案：A

07

view sourceprint?
01 var foo = {  

02     bar: function () {  

03         return this.baz;  

04     },  

05     baz: 1  

06 };  

07 typeof (f = foo.bar)();  

08    

09 A. "undefined" 

10 B. "object" 

11 C. "number" 

12 D. "function" 
答案：A

08

view sourceprint?
01 var f = (function f() {  

02     return "1";  

03 }, function g() {  

04     return 2;  

05 })();  

06 typeof f;  

07    

08 A. "string" 

09 B. "number" 

10 C. "function" 

11 D. "undefined" 
答案： B

09

view sourceprint?
01 var x = 1;  

02 if (function f() {}) {  

03     x += typeof f;  

04 }  

05 x;  

06    

07 A. 1  

08 B. "1function" 

09 C. "1undefined" 

10 D. NaN 
答案： C

10

view sourceprint?
1 var x = [typeof x, typeof y][1];  

2 typeof typeof x;  

3    

4 A. "number" 

5 B. "string" 

6 C. "undefined" 

7 D. "object" 
答案： B

11

view sourceprint?
01 (function (foo) {  

02     return typeof foo.bar;  

03 })({  

04     foo: {  

05         bar: 1  

06     }  

07 });  

08    

09 A、“undefined”   

10 B、“object”   

11 C、“number”   

12 D、Error 
答案： A

12

view sourceprint?
01 (function f() {  

02     function f() {  

03         return 1;  

04     }  

05     return f();  

06    

07     function f() {  

08         return 2;  

09     }  

10 })();  

11    

12 A、1   

13 B、2   

14 C、Error (e.g. “Too much recursion”)   

15 D、undefined 
答案：B

13

view sourceprint?
1 function f() {  

2     return f;  

3 }  

4 new f() instanceof f;  

5    

6 A、true   

7 B、false 
答案：B

14

view sourceprint?
1 with (function(x, undefined){}) length;  

2    

3 A、1   

4 B、2   

5 C、undefined   

6 D、Error 
答案：B

具体答案大家可以自己运行得出，为什么会得出这样的结果，我也有一些不懂的地方，怕误人子弟，所以这里就不解答这里的问题了。