JavaScript Regular Expressions 2

Question 1

What does the `*` quantifier mean in a regular expression?

Accepted Answer

Zero or more occurrences of the preceding token

Answer

`*` is a greedy quantifier that matches zero or more consecutive occurrences of the preceding element, making it optional.

Question 2

When `String.prototype.match()` is called with a regex that has the `g` flag, what does it return?

Accepted Answer

An array containing all matched substrings

Answer

With the `g` flag, `match()` returns a flat array of all matched strings; without it, it returns a detailed array-like object for only the first match.

Question 3

What does the syntax `(?:...)` create in a regular expression?

Accepted Answer

A non-capturing group that groups tokens without saving the match

Answer

`(?:...)` creates a non-capturing group, which groups part of the pattern for quantifiers or alternation but does not save the matched text as a capture group.

Question 4

What does `\b` represent in a regular expression?

Accepted Answer

A word boundary between a word character and a non-word character

Answer

`\b` is a zero-width assertion matching the position between a `\w` character and a `\W` character (or start/end of string), enabling whole-word matching.

Question 5

What does `RegExp.prototype.exec(str)` return when the pattern matches?

Accepted Answer

An array containing the full match and any captured groups, with index and input properties

Answer

`exec()` returns a result array with the full match at index 0, each capture group in subsequent indices, plus `index` and `input` properties — or `null` if no match.

JavaScript Practice Test

JavaScript Practice Test

JavaScript Regular Expressions 2