JavaScript Regular Expressions are quite same as PHP Regular Expressions.
Syntax
var check = /pattern/modifiers;
- pattern specifies the pattern of an expression
- modifiers specify if a search should be global, case-sensitive, etc.
Modifiers
Modifiers are used to perform case-insensitive and global searches:
| Modifier | Description |
|---|---|
| i | Perform case-insensitive matching |
| g | Perform a global match (find all matches rather than stopping after the first match) |
| m | Perform multiline matching |
Brackets
Brackets are used to find a range of characters:
| Expression | Description |
|---|---|
| [abc] | Find any character between the brackets |
| [^abc] | Find any character not between the brackets |
| [0-9] | Find any digit from 0 to 9 |
| [A-Z] | Find any character from uppercase A to uppercase Z |
| [a-z] | Find any character from lowercase a to lowercase z |
| [A-z] | Find any character from uppercase A to lowercase z |
| [adgk] | Find any character in the given set |
| [^adgk] | Find any character outside the given set |
| (red|blue|green) | Find any of the alternatives specified |
Metacharacters
Metacharacters are characters with a special meaning:
| Metacharacter | Description |
|---|---|
| . | Find a single character, except newline or line terminator |
| w | Find a word character |
| W | Find a non-word character |
| d | Find a digit |
| D | Find a non-digit character |
| s | Find a whitespace character |
| S | Find a non-whitespace character |
| b | Find a match at the beginning/end of a word |
| B | Find a match not at the beginning/end of a word |
| Find a NUL character | |
| n | Find a new line character |
| f | Find a form feed character |
| r | Find a carriage return character |
| t | Find a tab character |
| v | Find a vertical tab character |
| xxx | Find the character specified by an octal number xxx |
| xdd | Find the character specified by a hexadecimal number dd |
| uxxxx | Find the Unicode character specified by a hexadecimal number xxxx |
Quantifiers
| Quantifier | Description |
|---|---|
| n+ | Matches any string that contains at least one n |
| n* | Matches any string that contains zero or more occurrences of n |
| n? | Matches any string that contains zero or one occurrences of n |
| n{X} | Matches any string that contains a sequence of X n‘s |
| n{X,Y} | Matches any string that contains a sequence of X to Y n‘s |
| n{X,} | Matches any string that contains a sequence of at least X n‘s |
| n$ | Matches any string with n at the end of it |
| ^n | Matches any string with n at the beginning of it |
| ?=n | Matches any string that is followed by a specific string n |
| ?!n | Matches any string that is not followed by a specific string n |
RegExp Object Properties
| Property | Description |
|---|---|
| global | Specifies if the “g” modifier is set |
| ignoreCase | Specifies if the “i” modifier is set |
| lastIndex | The index at which to start the next match |
| multiline | Specifies if the “m” modifier is set |
| source | The text of the RegExp pattern |
RegExp Object Methods
| Method | Description |
|---|---|
| compile() | Compiles a regular expression |
| exec() | Tests for a match in a string. Returns the first match |
| test() | Tests for a match in a string. Returns true or false |