HTML and CSS Reference
In-Depth Information
EXAMPLE
17.13 (
CONTINUED
)
document.write(result+"<br />");
if (result){
document.write("<b>The reg_ex /[A-Za-z0-9_]/ matched the
string\""+ textString +"\".<br />");
}
else{
alert("No Match!");
}
</script>
</body>
</html>
EXPLANATION
1
A regular expression object, an alphanumeric character in the bracketed character
class
[A-Za-z0-9_]
is assigned to the variable called
reg_expression
. This regular
expression matches a string that contains at least one character in the character
class ranging between
A
and
Z
,
a
and
z
,
0
and
9
, and the underscore character, _.
2
User input is entered in the prompt dialog box and assigned to the variable
text-
String
. In this example the user entered
Take 5
.
3
The regular expression test method will return
true
because this string
Take 5
con-
tains at least one alphanumeric character (see Figure 17.14).
Figure 17.14
User entered
Take 5
(top). The string contained at least one
alphanumeric character (bottom).
EXAMPLE
17.14
<html>
<head><title>The Character Class and Negation</title></head>
<body>
