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Extended string methods

In this code,

arrMatches

contains three items: the

“at”

from

“bat”

“Cat”

, and

“cat”

. To return all

instances of

, regardless of the case, just add the

option:

var sToMatch = “a bat, a Cat, a fAt baT, a faT cat”;

var reAt = /at/gi;

var arrMatches = reAt.exec(sToMatch);

Now

arrMatches

contains all of the instances of

“at”

, regardless of position or case. Note that the

instances of

“at”

with uppercase letters will be stored in

arrMatches

the same way that they appear

sToMatch

. Here are the contents of the

arrMatches

array after this code executes:

Index

Value

From

“at”

“bat”

“at”

“Cat”

“At”

“fAt”

“aT”

“baT”

“aT”

“faT”

“at”

“cat”

The

String

object has a method called

match()

, which intentionally mirrors the functionality of the

RegExp

object’s

exec()

method. The main difference is that the method is called on the

String

object

and the

RegExp

object is passed in as an argument:

var sToMatch = “a bat, a Cat, a fAt baT, a faT cat”;

var reAt = /at/gi;

var arrMatches = sToMatch.match(reAt);

This code yields the same result as the previous example, with

arrMatches

containing all the same

items.

A String method calls

search()

that acts the same way as

indexOf()

, but uses a

RegExp

object instead

of a substring. The

search()

method returns the index of the first occurrence in the string:

var sToMatch = “a bat, a Cat, a fAt baT, a faT cat”;

var reAt = /at/gi;

alert(sToMatch.search(reAt)); //outputs “3”

In this example, the alert will display

“3”

, because the first occurrence of

“at”

is at position 3 in the

string. Specifying the regular expression as global (with the

) has no effect when using

search()

Extended string methods

Two String methods, discussed earlier in the book, also accept regular expressions as parameters. The

first is the

replace()

method, which replaces all occurrences of a substring (the first argument) with a

different string (the second argument). For example:

195

Regular Expressions

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