This is a regular expression parser, written in JavaScript as a learning exercise - if you need to parse a regular expression in JavaScript you should of course use the built-in RegExp class, and not this implementation.
This library implements a backtracking recursive descent parser and uses this grammar to construct a parse tree from the regular expression text that you supply. The parse tree is encapsulated within a regex object, and returned by the parse.compile() function. The regex object exposes a match() method that can be used to test string values against the expression. The result of a match is contained within an object that has a matches property, set to either true or false to indicate whether the match succeeded or not.
var regex, match;
regex = parser.compile('abc+');
match = regex.match('abccc'); // match.matches = true
match = regex.match('abcd'); // match.matches = false
The library supports the following symbols:
| Symbol | Example |
|---|---|
| * (zero or more) | abc* |
| + (one or more) | abc+ |
| ? (zero or one) | abc? |
| . (any single character) | a.b.c |
| [ ] (inclusive character specification) | [A-C][a-c][123] |
| [^ ] (exclusive character specification) | [^A-C][^a-c][^123] |
| { } (exact number of matches) | a{5} |
| { , } (range of matches) | a{3,5} |
| { ,} (lower bounded number of matches) | a{3,} |
| | (alternatives) | dog|cat|hamster |
| () (parentheses) | d(i|u|o)g |
| () \1 (capturing groups) | (1|2|3)==\1 |
| \s and \S (whitespace/non-whitespace alias) | \S\s\S\s\S |
| \d and \D (digit/non-digit alias) | \d\D\d |
You can try some live examples on the project homepage