The RegExp Object The regular expression object describes a pattern of characters. Syntax for creating a RegExp object: var txt=...
The RegExp Object
The regular expression object describes a pattern of characters.Syntax for creating a RegExp object:
var txt=new RegExp(pattern,attributes); or var txt=/pattern/attributes; |
- pattern specifies the pattern of the regular expression
- attributes specifies global ("g"), case-insensitive ("i"), and multiline matches ("m")
RegExp Object Properties
FF: Firefox, N: Netscape, IE: Internet Explorer| Property | Description | FF | N | IE |
|---|---|---|---|---|
| global | Specifies if the "g" modifier is set | 1 | 4 | 4 |
| ignoreCase | Specifies if the "i" modifier is set | 1 | 4 | 4 |
| input | The string on which the pattern match is performed | 1 | 4 | 4 |
| lastIndex | An integer specifying the index at which to start the next match | 1 | 4 | 4 |
| lastMatch | The last matched characters | 1 | 4 | 4 |
| lastParen | The last matched parenthesized substring | 1 | 4 | 4 |
| leftContext | The substring in front of the characters most recently matched | 1 | 4 | 4 |
| multiline | Specifies if the "m" modifier is set | 1 | 4 | 4 |
| prototype | Allows you to add properties and methods to the object | 1 | 4 | 4 |
| rightContext | The substring after the characters most recently matched | 1 | 4 | 4 |
| source | The text used for pattern matching | 1 | 4 | 4 |
RegExp Object Methods
| Method | Description | FF | N | IE |
|---|---|---|---|---|
| compile() | Change the regular expression | 1 | 4 | 4 |
| exec() | Search a string for a specified value. Returns the found value and remembers the position | 1 | 4 | 4 |
| test() | Search a string for a specified value. Returns true or false | 1 | 4 | 4 |
String Object Methods that supports Regular Expressions
| Method | Description | FF | N | IE |
|---|---|---|---|---|
| search() | Search a string for a specified value. Returns the position of the value | 1 | 4 | 4 |
| match() | Search a string for a specified value. Returns an array of the found value(s) | 1 | 4 | 4 |
| replace() | Replace characters with other characters | 1 | 4 | 4 |
| split() | Split a string into an array of strings | 1 | 4 | 4 |
RegExp Modifiers
| Modifier | Description | FF | N | IE |
|---|---|---|---|---|
| i | Perform case-insensitive matching | 1 | 4 | 4 |
| g | Perform a global match. Find all matches (do not stop after the first match) | 1 | 4 | 4 |
| gi | Perform a global case-insensitive match. Find all matches (do not stop after the first match) | 1 | 4 | 4 |
| m | Perform multiline matching | 1 | 4 | 4 |
RegExp Modifiers
| Property | Description | FF | N | IE |
|---|---|---|---|---|
| Position Matching | ||||
| ^ | Get a match at the beginning of a string | 1 | 4 | 4 |
| $ | Get a match at the end of a string | 1 | 4 | 4 |
| \b | Word boundary. Get a match at the beginning or end of a word in the string | 1 | 4 | 4 |
| \B | Non-word boundary. Get a match when it is not at the beginning or end of a word in the string | 1 | 4 | 4 |
| ?= | A positive look ahead. Get a match if a string is followed by a specific string | 1 | 4 | 4 |
| ?! | A negative look ahead. Get a match if a string is not followed by a specific string | 1 | 4 | 4 |
Literals | ||||
| \0 | Find a NULL character | 1 | 4 | 4 |
| \n | Find a new line character | 1 | 4 | 4 |
| \f | Find a form feed character | 1 | 4 | 4 |
| \r | Find a carriage return character | 1 | 4 | 4 |
| \t | Find a tab character | 1 | 4 | 4 |
| \v | Find a vertical tab character | 1 | 4 | 4 |
| \xxx | Find the ASCII character expressed by the octal number xxx | 1 | 4 | 4 |
| \xdd | Find the ASCII character expressed by the hex number dd | 1 | 4 | 4 |
| \uxxxx | Find the ASCII character expressed by the UNICODE xxxx | 1 | 4 | 4 |
Character Classes | ||||
| [xyz] | Find any character in the specified character set | 1 | 4 | 4 |
| [^xyz] | Find any character not in the specified character set | 1 | 4 | 4 |
| . (dot) | Find any character except newline or line terminator | 1 | 4 | 4 |
| \w | Find any alphanumeric character including the underscore | 1 | 4 | 4 |
| \W | Find any non-word character | 1 | 4 | 4 |
| \d | Find any single digit | 1 | 4 | 4 |
| \D | Find any non-digit | 1 | 4 | 4 |
| \s | Find any single space character | 1 | 4 | 4 |
| \S | Find any single non-space character | 1 | 4 | 4 |
Repetition | ||||
| {x} | Finds the exact (x) number of the regular expression grouped together | 1 | 4 | 4 |
| {x,} | Finds the exact (x) or more number of the regular expression grouped together | 1 | 4 | 4 |
| {x,y} | Finds between x and y number of the regular expression grouped together | 1 | 4 | 4 |
| ? | Finds zero or one occurrence of the regular expression | 1 | 4 | 4 |
| * | Finds zero or more occurrences of the regular expression | 1 | 4 | 4 |
| + | Finds one or more occurrences of the regular expression | 1 | 4 | 4 |
Grouping | ||||
| ( ) | Finds the group of characters inside the parentheses and stores the matched string | 1 | 4 | 4 |
| (?: ) | Finds the group of characters inside the parentheses but does not store the matched string | 1 | 4 | 4 |
| | | Combines clauses into one regular expression and then matches any of the individual clauses. Similar to "OR" statement | 1 | 4 | 4 |
Back references | ||||
| ( )\n | Back reference. Uses the stored matched string. i.e. from the ( ) modifier | 1 | 4 | 4 |
