HTML and CSS Reference
In-Depth Information
Figure H-6
Methods of regular expression objects
Method
Description
re .compile( pattern,
modifiers )
compiles or recompiles a regular expression re , where pattern
is the text string of the new regular expression pattern and
modifiers contains modifiers applied to the pattern
re .exec( string )
executes a search on string using the regular expression re ;
pattern results are returned in an array and reflected in the
properties of the global RegExp object
re .match( string )
performs a pattern match on string using the re regular expres-
sion; matched substrings are stored in an array
string .replace
( re , newsubstr )
replaces the substring defined by the regular expression re in the
text string string with newsubstr
string .search( re )
searches string for a substring matching the regular expression
re ; returns the index of the match, or -1 if no match is found
string .split( re )
splits string at each point indicated by the regular expression re ;
the substrings are stored in an array
re .test( string )
performs a pattern match on the text string string using the regu-
lar expression re , returning the Boolean value true if a match is
found and false otherwise
Validating a Postal Code using Regular Expressions
You can use JavaScript and regular expressions to validate a variety of text patterns. For
example, you may have Web form in which you need to validate a recipient's postal
code. The following function demonstrates how to employ a regular expression that
matches either a five-digit or nine-digit zip code or an empty text string (when the postal
code is not required for delivery). The regular expression is
/^\d{5}(-\d{4})?$|^$/
This regular expression matches zip codes in the form nnnnn or nnnnn-nnnn ; it also
uses the alternation character | to allow for empty text strings. You can use this regular
expression in the following function:
function checkZipRE(zip) {
var regx = /^\d{5}(-\d{4})?$|^$/;
return regx.test(zip);
}
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