Array And Function MCQ question and answer in javascript with solution

1

Consider the code snippet given below

var count = [1,,3];

What is the observation made?

A) The omitted value takes “undefined” B) This results in an error C) This results in an exception D) None of the mentioned

Discuss

Answer & Solution

Answer: Option A

Solution:

If you omit a value from an array literal, the omitted element is given the value.

2

Consider the following code snippet

var a1 = [,,,]; 
var a2 = new Array(3); 
0 in a1 
0 in a2

The result would be

A) true false B) false true C) true true D) None of the above

Discuss

Answer & Solution

Answer: Option A

Solution:

a1 has an element with index 0 and a2 has no element with index 0.

3

The pop() method of the array does which of the following task ?

A) decrements the total length by 1 B) increments the total length by 1 C) prints the first element but no effect on the length D) None of the mentioned

Discuss

Answer & Solution

Answer: Option A

Solution:

Arrays have a pop() method (it works with push()) that reduces the length of an array by 1 but also returns the value of the deleted element.

4

Consider the following code snippet :

if (!a[i]) continue ;

What is the observation made ?

A) Skips the undefined elements B) Skips the non existent elements C) Skips the null elements D) All of the mentioned

Discuss

Answer & Solution

Answer: Option D

No explanation is given for this question. Let's Discuss on Board

5

What will happen if reverse() and join() methods are used simultaneously ?

A) Reverses and stores in the same array B) Reverses and concatenates the elements of the array C) Reverses D) All of the mentioned

Discuss

Answer & Solution

Answer: Option A

Solution:

The reverse() followed by a join() will reverse the respective array and will store the reversed array in the memory.

6

Consider the following code snippet :

var a = [1,2,3,4,5];
a.slice(0,3);

What is the possible output for the above code snippet ?

A) Returns [1,2,3] B) Returns [4,5] C) Returns [1,2,3,4] D) Returns [1,2,3,4,5]

Discuss

Answer & Solution

Answer: Option A

No explanation is given for this question. Let's Discuss on Board

7

Consider the following code snippet :

var a = []; 
a.unshift(1); 
a.unshift(22);
a.shift(); 
a.unshift(3,[4,5]); 
a.shift(); 
a.shift();
a.shift();

The final output for the shift() is

A) 1 B) [4,5] C) [3,4,5] D) Exception is thrown

Discuss

Answer & Solution

Answer: Option A

Solution:

The unshift() and shift() methods behave much like push() and pop(), except that they insert and remove elements from the beginning of an array rather than from the end. unshift() adds an element or elements to the beginning of the array, shifts the existing array elements up to higher indexes to make room, and returns the new length of the array. shift() removes and returns the first element of the array, shifting all subsequent elements down one place to occupy the newly vacant space at the start of the array.

8

The primary purpose of the array map() function is that it

A) maps the elements of another array into itself B) passes each element of the array and returns the necessary mapped elements C) passes each element of the array on which it is invoked to the function you specify, and returns an array containing the values returned by that function D) None of the mentioned

Discuss

Answer & Solution

Answer: Option C

Solution:

The map() method passes each element of the array on which it is invoked to the functionyou specify, and returns an array containing the values returned by that function.

9

The reduce and reduceRight methods follow a common operation called

A) filter and fold B) inject and fold C) finger and fold D) fold

Discuss

Answer & Solution

Answer: Option B

No explanation is given for this question. Let's Discuss on Board

10

The method or operator used to identify the array is

A) isarrayType() B) == C) === D) typeof

Discuss

Answer & Solution

Answer: Option D

Solution:

The typeof property is used to identify the array type.