Writing Scripts in Nashorn - Scripting in Java: Integrating with Groovy and JavaScript - page 151

Regular expressions are very powerful features of any programming language. Java
supports regular expressions. If you are familiar with regular expression in Java or Perl,
the following discussion will be easy to follow. The pattern in a regular expression may be
very complex. Typically, the letters and digits in the pattern match the input text literally.
For example, the regular expression /Java/ will try to match the word Java at any
position in the input text. The following code uses the test() method to check if a regular
expression matches the input text:

var pattern = new RegExp("Java"); // Same as var pattern = /Java/;
var match = pattern.test("JavaScript");
print(pattern + " matches \"JavaScript\": " + match);

// Perfoms a case-sensitive match that is the default
var match2 = /java/.test("JavaScript");
print("/java/ matches \"JavaScript\": " + match2);

// Performs a case-insensitive match using the i flag
var match3 = /java/i.test("JavaScript");
print("/java/i matches \"JavaScript\": " + match3);

/Java/ matches "JavaScript": true
/java/ matches "JavaScript": false
/java/i matches "JavaScript": true

The RegExp object has four properties, as listed in Table 4-17 . The source ,
global , ignoreCase , and multiline properties are read-only, nonenumerable, and
nonconfigurable, and they are set at the time you create the regular expression. The
lastIndex property is writable, nonenumerable, and nonconfigurable.

Table 4-17. The List of Methods in the RegExp.prototype Object

Property Description

source A string that is the pattern part of the RegExp object. If you create a regular
expression using new RegExp("Java", "gm") , the source property of the
object is set to “Java”
global It is a Boolean value that is set to true if the flag g is used, false otherwise
ignoreCase It is a Boolean value that is set to true if the flag i is used, false otherwise
multiline

It is a Boolean value that is set to true if the flag m is used, false
otherwise

lastIndex It is an integer value that specifies the position in the input text where the

next match will start. It is set to zero when the RegExp object is created.
It may change automatically when you perform a match or you can
change it in code