Questions and answers for exam Preparation

MCQs

Total Questions : 9

Question 1. The pop() method of the array does which of the following task ?

decrements the total length by 1
increments the total length by 1
prints the first element but no effect on the length
None of the above

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Answer: Option A. -> decrements the total length by 1

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.

Question 2. Consider the following statementsvar text = "testing: 1, 2, 3"; // Sample textvar pattern = /\d+/g // Matches all instances of one or more digitsIn order to check if the pattern matches with the string "text, the statement is

text==pattern
text.equals(pattern)
text.test(pattern)
pattern.test(text)

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Answer: Option D. -> pattern.test(text)

The given pattern is applied on the text given in the parenthesis.

Question 3. What is the fundamental rule of lexical scoping?

Functions are declared in the scope
Functions are executed using scope chain
Both a and b
None of the mentioned

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Answer: Option B. -> Functions are executed using scope chain

The fundamental rule of lexical scoping is that the JavaScript functions are executed using the scope chain that was in effect when they were defined.

Question 4. 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();

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Answer: Option C. -> var o= new Object;

You can always omit a pair of empty parentheses in a constructor invocation.

Question 5. 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

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Answer: Option C. -> It returns the undefined value

If the return statement does not have an associated expression, it returns the undefined value.

Question 6. JavaScript Code can be called by using

RMI
Triggering Event
Preprocessor
Function/Method

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Answer: Option D. -> Function/Method

None

Question 7. One of the special feature of an interpreter in reference with the for loop is that

Before each iteration, the interpreter evaluates the variable expression and assigns the name of the property
The iterations can be infinite when an interpreter is used
The body of the loop is executed only once
All of the mentioned

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Answer: Option A. -> Before each iteration, the interpreter evaluates the variable expression and assigns the name of the property

Before each iteration, the interpreter evaluates the variable expression and assigns the name of the property (a string value) to it.

Question 8. Consider the following code snippetfunction f(o) { if (o === undefined) debugger;}What could be the task of the statement debugger?

It does nothing but a simple breakpoint
It debugs the error in that statement and restarts the statement's execution
It is used as a keyword that debugs the entire program at once
All of the mentioned

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Answer: Option A. -> It does nothing but a simple breakpoint

The debugger statement normally does nothing. If, however, a debugger program is available and is running, then an implementation may (but is not required to) perform some kind of debugging action. In practice, this statement acts like a breakpoint: execution of JavaScript code stops and you can use the debugger to print variable's values.

Question 9. Consider the below given syntaxbook[datatype]=assignment_value;In the above syntax, the datatype within the square brackets must be