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In-Depth Information
<head><title>The Word Boundary</title></head>
<script type="text/javascript">
// Anchoring a word with \b
var reg_expression = /\blove\b/;
var textString=prompt("Type a string of text","");
var result=reg_expression.test(textString) ;// Returns true
// or false
document.write(result+"<br />");
if (result){
document.write("<b>The regular expression /\blove\b/
matched the string \""+ textString +"\".<br />");
alert("No Match!");
The regular expression contains the \b metacharacter, representing a word bound-
ary, not a specific character. The expression reads: Find a word beginning and
ending with love . This means that gloves, lover, clover, and so on, will not be found.
The regular expression test() method will return true because the string love is
within word boundary anchors \b . See Figure 17.32.
Figure 17.32 The user entered Iloveyou! . The word love is between word
boundaries ( \b ). The match was successful.
17.4.6 Alternation
Alternation allows the regular expression to contain alternative patterns to be matched;
for example, the regular expression / John|Karen|Steve / will match a line containing John
or Karen or Steve . If Karen, John , or Steve are all on different lines, all lines are matched.
Each of the alternative expressions is separated by a vertical bar (the pipe symbol, | ) and
the expressions can consist of any number of characters, unlike the character class that
only matches for one character; thus, /a|b|c/ is the same as [abc] , whereas /ab|de/ cannot
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