JavaScript Regular Expressions Quiz

1. The i flag in a regular expression makes the pattern case-insensitive.

True False

The i flag stands for "ignore case".

True - The i flag makes the regex match both uppercase and lowercase letters.

2. The g flag causes the regex to stop after finding the first match.

True False

The g stands for "global".

False - The g flag makes the regex find all matches, not just the first one.

3. The * quantifier matches zero or more occurrences of the preceding element.

True False

Think about how many times the preceding character can appear.

True - The * matches 0 or more occurrences.

4. The ? quantifier matches exactly two occurrences of the preceding element.

True False

The ? makes something optional.

False - The ? matches 0 or 1 occurrence (makes it optional).

5. The + quantifier matches one or more occurrences of the preceding element.

True False

Compare this to * which includes zero occurrences.

True - The + requires at least one occurrence.

6. In JavaScript, regular expression literals are enclosed in forward slashes /.

True False

Think about the syntax: /pattern/flags

True - JavaScript regex literals use forward slashes as delimiters.

7. The character class [acg] matches any single character that is 'a', 'c', or 'g'.

True False

Square brackets define a character class.

True - Character classes match any one of the characters inside the brackets.

8. The pattern [a-z] matches only lowercase letters from 'a' to 'z'.

True False

The hyphen in a character class indicates a range.

True - The a-z range matches lowercase letters only.

9. What does the i flag do in the regex /hello/i?

Makes the regex match only integers Makes the regex case-insensitive Makes the regex match inline only Makes the regex ignore whitespace

This flag affects how the regex treats uppercase vs lowercase.

B - The i flag makes the pattern case-insensitive.

10. What is the purpose of the g flag in JavaScript regex?

To match only groups To find all matches instead of just the first To make the regex greedy To group characters together

Think about "global" searching.

B - The g flag performs a global search (finds all matches).

11. How many times does a* match the letter 'a'?

Exactly once At least once Zero or more times Exactly twice

The * includes the possibility of zero matches.

C - The * quantifier matches zero or more occurrences.

12. What does the ? quantifier mean in regex?

Match two or more times Match zero or one time Match any character End of pattern

The ? makes the preceding element optional.

B - The ? matches zero or one occurrence (optional).

13. What is the minimum number of matches for the + quantifier?

Zero One Two Three

The + requires at least one match.

B - The + matches one or more times (minimum of 1).

14. Which of the following is the correct syntax for a regex literal in JavaScript?

"pattern" /pattern/ (pattern) [pattern]

Regex literals use a special delimiter character.

B - Forward slashes enclose regex patterns in JavaScript.

15. What will [acg] match in the string "bag"?

Only 'a' 'a' and 'g' The entire string "acg" Nothing

Character classes match individual characters that are in the set.

B - It matches 'a' and 'g' (any character in the brackets).

16. What does [a-z] NOT match?

'm' 'z' 'A' 'a'

Pay attention to uppercase vs lowercase.

C - [a-z] matches lowercase only, not uppercase 'A'.

17. To make a regex pattern case-insensitive, you add the ____ flag.

This flag stands for "ignore case".

i

18. The ____ flag is used to find all matches in a string, not just the first one.

This flag stands for "global".

g

19. The ____ quantifier matches zero or more occurrences of the preceding element.

This symbol is commonly called an asterisk or star.

*

20. To make a character optional in a regex, use the ____ quantifier.

This symbol is a question mark.

?

21. The ____ quantifier matches one or more occurrences of the preceding element.

This symbol is a plus sign.

+

22. In JavaScript, regex literals are enclosed in ____ characters.

These are the same characters used in division and URLs.

/

23. To match any one of the characters a, c, or g, you would write ____.

Use square brackets to create a character class.

[acg]

24. To match any lowercase letter from a to z, write ____.

Use a hyphen to indicate a range within square brackets.

[a-z]