Array And Function(Javascript ) Questions and answers for exam Preparation

Question 1. When does the function name become optional in JavaScript?

When the function is defined as a looping statement
When the function is defined as expressions
When the function is predefined
All of the mentioned

Explanation:-

Answer: Option B. -> When the function is defined as expressions
The function name is optional for functions defined as expressions. A function declaration statement actually declares a variable and assigns a function object to it.

Question 2. Consider the following code snippet
function printprops(o)
{
for(var p in o)
console.log(p + ": " + o[p] + "n");
}
What will the above code snippet result ?

Prints the contents of each property of o
Returns undefined
All of the mentioned
None of the mentioned

Explanation:-

Answer: Option B. -> Returns undefined
The above code snippet returns undefined.

Question 3. The function definitions in JavaScript begins with

Identifier and Parantheses
Return type and Identifier
Return type, Function keyword, Identifier and Parantheses
Identifier and Return type

Explanation:-

Answer: Option A. -> Identifier and Parantheses
The function definitions begin with the keyword function followed by an identifier that names the function and a pair of parantheses around a comma-separated list of zero or more identifiers.

Question 4. What will happen if a return statement does not have an associated expression?

It returns the value 0
It will throw an exception
It returns the undefined value
None of the mentioned

Explanation:-

Answer: Option C. -> It returns the undefined value
If the return statement does not have an associated expression, it returns the undefined value.

Question 5. What is the purpose of a return statement in a function?

Returns the value and continues executing rest of the statements, if any
Returns the value and stops the program
Returns the value and stops executing the function
Stops executing the function and returns the value

Explanation:-

Answer: Option D. -> Stops executing the function and returns the value
The return statement causes the function to stop executing and to return the value of its expression (if any) to the caller.

Question 6. Do functions in JavaScript necessarily return a value ?

It is mandatory
Not necessary
Few functions return values by default
All of the mentioned

Explanation:-

Answer: Option C. -> Few functions return values by default

Question 7. Consider the following code snippet :
var string2Num=parseInt("123xyz");
The result for the above code snippet would be :

123
123xyz
Exception
NaN

Explanation:-

Answer: Option B. -> 123xyz
The parseInt() function returns the first integer contained in the string or 0 if the string does not begin with an integer.

Question 8. For the below mentioned code snippet:
var o = new Object();
The equivalent statement is:

var o = Object();
var o;
var o= new Object;
Object o=new Object();

Explanation:-

Answer: Option C. -> var o= new Object;
You can always omit a pair of empty parentheses in a constructor invocation.

Question 9. Consider the following code snippet :
var tensquared = (function(x) {return x*x;}(10));
Will the above code work ?

Yes, perfectly
Error
Exception will be thrown
Memory leak

Explanation:-

Answer: Option A. -> Yes, perfectly
Function name is optional for functions defined as expressions. Function expressions are sometimes defined and immediately invoked.

Question 10. If you have a function f and an object o, you can define a method named m of o with

o.m=m.f;
o.m=f;
o=f.m;
o=f;

Explanation:-

Answer: Option A. -> o.m=m.f;
A method is nothing more than a JavaScript function that is stored in a property of an object. If you have a function f and an object o, you can define a method named m of o with the following line:
o.m = f;