Classes And Modules MCQ question and answer in javascript with solution

31

Consider the following statement containing regular expressions

var text = "testing: 1, 2, 3"; 
var pattern = /d+/g;

In order to check if the pattern matches, the statement is

A) text==pattern B) text.equals(pattern) C) text.test(pattern) D) pattern.test(text)

Discuss

Answer & Solution

Answer: Option D

Solution:

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

32

The regular expression to match any one character not between the brackets is

A) […] B) [^] C) [^…] D) [D]

Discuss

Answer & Solution

Answer: Option C

Solution:

The [^…] character class is used to match or draw any one character not between the brackets.

33

What does /[^(]* regular expression indicate ?

A) Match one or more characters that are not open paranthesis B) Match zero or more characters that are open paranthesis C) Match zero or more characters that are not open paranthesis D) Match one or more characters that are open paranthesis

Discuss

Answer & Solution

Answer: Option C

Solution:

We should always be careful while using * and ? as repetition characters as they may match zero instances of whatever precedes them, they are allowed to match nothing.

34

What will be the result when non greedy repetition is used on the pattern /a+?b/ ?

A) Matches the letter b preceded by the fewest number of a’s possible B) Matches the letter b preceded by any number of a C) Matches letter a preceded by letter b, in the stack order D) None of the mentioned

Discuss

Answer & Solution

Answer: Option A

Solution:

Using non greedy repetition may not always produce the results you expect. /a+?b/ matches the letter b preceded by the fewest number of a’s possible.

35

What does the subexpression /java(script)?/ result in ?

A) It matches “java” followed by the optional “script” B) It matches “java” followed by any number of “script” C) It matches “java” followed by a minimum of one “script” D) None of the mentioned

Discuss

Answer & Solution

Answer: Option A

Solution:

The subexpression /java(script)?/ matches “java” followed by the optional “script”.

36

What is the most essential purpose of parantheses in regular expressions ?

A) Define pattern matching techniques B) Define subpatterns within the complete pattern C) Define portion of strings in the regular expression D) All of the mentioned

Discuss

Answer & Solution

Answer: Option B

Solution:

When a regular expression is successfullyy matched against a target string, it is possible to extract the portions of the target string that matched any particular paranthesized subpattern. The essential purpose of parantheses in regular expressions is to define subpatterns within the complete pattern.

37

The method that performs the search-and-replace operation to strings for pattern matching is

A) searchandreplace() B) add() C) edit() D) replace()

Discuss

Answer & Solution

Answer: Option B

Solution:

The replace() method performs a search-and-replace operation. It takes a regular expression as its first argument and a replacement string as its second argument.

38

What would be the result of the following statement in JavaScript using regular expression methods ?

A) Returns [“123″”456″”789”] B) Returns [“123″,”456″,”789”] C) Returns [1,2,3,4,5,6,7,8,9] D) Throws an exception

Discuss

Answer & Solution

Answer: Option B

Solution:

The split() method can take regular expressions as its arguments. The split() method generally breaks the string on which it is called into an array of substrings, using the argument as a separator.

39

The Crockford’s subset doesnot include which function in JavaScript?

A) eval() B) coeval() C) equal() D) equivalent()

Discuss

Answer & Solution

Answer: Option A

Solution:

The Crockford’s subset does not include the with and continue statements or the eval() function. It defines functions using function definition expressions only and does not include the function definition statement.

40

Why does JavaScript subset disallow == and !=?

A) It uses bitwise checking B) It uses === and !== instead C) It uses equals() and notequals() instead D) None of the mentioned

Discuss

Answer & Solution

Answer: Option B

Solution:

The subset does not include the comma operator, the bitwise operators, or the ++ and — operators. It also disallows == and != because of the type conversion they perform, requiring use of === and !== instead.