30 javascript questions and answers that you "cannot do all" (1)

30 javascript questions and answers that you "cannot do all" (1)

1. The running result of the following expression is:

["1", "2", "3"]. map (parseInt)

A. ["1", "2", "3"]

B. [1, 2, 3]

C. [0, 1, 2]

D. Miscellaneous

2. The running result of the following expression is:

[Typeof null, null instanceof Object]

A. ["object", false]

B. [null, false]

C. ["object", true]

D. Miscellaneous

3. The running result of the following expression is:

[[3, 2, 1]. reduce (Math. pow), []. reduce (Math. pow)]

A. Error

B. [9, 0]

C. [9, NaN]

D. [9, undefined]

4. The running result of the following expression is:

Var val = 'value ';
Console.info ('value id' + (val = 'value ')? 'Something': 'Nothing ');

A. Something

B. Nothing

C. NaN

D. Miscellaneous

5. The running result of the following expression is:

Var name = 'World ';
(Function (){
If (typeof name = 'undefined '){
Var name = "Jack ";
Console.info ('Goodbye '+ name );
} Else {
Console.info ('hello' + name );
}
})();

A. Goodbye Jack

B. Hello Jack

C. Goodbye undefined

D. Hello undefined

6. The running result of the following expression is:

Var START = END-100;
Var count = 0;

For (var I = START; I <= END; I ++ ){
Count ++;
}
Lele.info (count );

A.0

B .100

C.101

D. Miscellaneous

7. The running result of the following expression is:

Var arr = [0, 1, 2];
Arr [10] = 10;
Arr. filter (function (x) {return x = undefined });

A. [undefined x 7]

B. [0, 1, 2, 10]

C. []

D. [undefined]

8. The running result of the following expression is:

Var two = 0.2;
Var one = 0.1;
Var eight = 0.8;
Var six= 0.6;
[Two-one = one, eight-six = two];

A. [true, true]

B. [false, false]

C. [true, false]

D. Miscellaneous

9. The running result of the following expression is:

Function showCase (value ){

Switch (value ){
Case 'A ':
Console.info ('case ');
Break;
Case 'B ':
Console.info ('case B ');
Break;
Case undefined:
Console.info ('undefined ');
Break;
Default:
Console.info ('Do not know! ');
}
}
ShowCase (new String ('A '));

A. Case

B. Case B

C. Do not know

D. undefined

10. The running result of the following expression is:

Function showCase (value ){

Switch (value ){
Case 'A ':
Console.info ('case ');
Break;
Case 'B ':
Console.info ('case B ');
Break;
Case undefined:
Console.info ('undefined ');
Break;
Default:
Console.info ('Do not know! ');
}
}
ShowCase (String ('A '));

A. Case

B. Case B

C. Do not know

D. undefined

11. The running result of the following expression is:

Function isOdd (num ){
Return num % 2 = 1;
}
Function isEven (num ){
Return num % 2 = 0;
}
Function isSane (num ){
Return isEven (num) | isOdd (num );
}
Var values = [7, 4, '13',-9, Infinity];
Values. map (isSane );

A. [true, true]

B. [true, true, false]

C. [true, false, false]

D. [true, true, false]

12. The running result of the following expression is:

[ParseInt (3,8), parseInt (3,2), parseInt (3,0)]

A. [3, 3]

B. [3, 3, NaN]

C. [3, NaN, NaN]

D. Miscellaneous

13. The running result of the following expression is:

Array. isArray (Array. prototype)

A. true

B. false

C. Error

D. Miscellaneous

14. The running result of the following expression is:

Var a = [0];
If ([0]) {
Console.info (a = true );
} Else {
Console.info ("else ");
}

A. true

B. false

C. "else"

D. Miscellaneous

15. The running result of the following expression is:

[] = []

A. true

B. false

C. Error

D. Miscellaneous