The *symbol is used to check if there are zero or more occurrences of the pattern to the left of the symbol. You can add quantifiers to specify how many characters should be included in the match at once. Specifying the Number of Times to MatchĪll the meta-characters given below can be used to evaluate patterns based on the number of times a character is repeated. The dollar symbol $ matches the end of the string. The caret symbol ^ matches the beginning of the string. \b matches the beginning or end of a word. \S matches all other characters except whitespace. Whitespace is equivalent to with bracket notation. This includes spaces, tabs, and line breaks. \d matches digit characters-any digit from 0 to 9. \W matches non-word characters: everything except alphanumeric characters and underscore. Word characters are alphanumeric (a-z, A-Z characters, and underscore). For example, matches any non-digit character. With a ^ symbol, the square brackets match any character not listed. The square brackets are used to specify a collection of characters. The period matches any character except the newline '\n'.
The following sequences can be used to match a specific set of characters. Var rgx = new RegExp('^(\d+)'): The constructor function is useful when the regular expression may change programmatically. This is evaluated at compile time and provides better performance if the regular expression stays constant. Var rgx = /^(\d+)/: You can use a regular expression literal and enclose the pattern between slashes. There are two ways of defining a regular expression in JavaScript. Parenthesis in Regular Expressions Regular Expression Methods in JavaScript FunctionĬreating a Regular Expression in JavaScript Using Flags With Regular Expressions Flag Specifying the Number of Times to Match Symbol Matching a Specific Set of Characters Operator Creating a Regular Expression in JavaScript Method This is a regular expressions cheat sheet which you can refer to when trying to remember how a method, special character, or flag works. Successfully working with regular expressions requires you to know what each special character, flag, and method does.
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