Java Script Pattern Matching Using Regular Expressions

Metacharacters Character class – [abc] matches ‘a’ or ‘b’ or ‘c’ – [a-z] matches a through z – [^aeiou] matches any character except a vowel ^ - beginning of the string $ - end of the string

Predefined Character Classes NameEquivalent PatternMatches \d[0-9]A digit \D[^0-9]Not a digit \w[A-Za-z_0-9]A word character (alphanumeric) \W[^A-Za-z_0-9]Not a word character \s[ \r\t\n\f]A whitespace character \S[^ \r\t\n\f]Not a whitespace character

Matches var matches = str.match(/^\d\.\d\d$/); matches 3.14 var matches = str.match(/^\w\w\w$/); var matches = str.match(/^\w{3}$/); matches abc or 123 or Abc

* + Metacharacters * = zero or more + = one or more var matches = str.match(/^\d+\.\d*$/); matches or 123. var matches = str.match(/^[A-Za-z]\w*$/); identifiers in programming languages

Social Security Number if( !document.forms[0].mySSN.value.match (/^\d{3}-\d{2}-\d{4}$/); {alert(“Invalid ssn.”); return false;} ^ = beginning of string $ = end of string

? Metacharacter Parse Zip Code var zipcode = str.match(/^\d{5}(-\d{4})?$/);

date If(str.match(/^1?\d\/\d?\d\/\d\d$/) == null) { alert(“invalid date”); } ? = zero or one

Trim date = date.trim();