Number of occurences using ?
If a pattern has ? , it means that the character preceding ? has either 0 or 1 occurrence. In other words, the character preceding ? is optional. Let us repeat the above example with ? in place of +..
<html>
<body>
<script type="text/javascript">
<!--
/*
********************************************************
Javascript Regular Expression Example 6
Number of occurrences with ?
********************************************************
*/
var pattern1=new RegExp("fo?d");
var string1 = new Array(5);
string1[0] = "food";
string1[1] = "fod";
string1[2] = "fd";
string1[3] = "foooood";
string1[4] = "fud";
var i;
for(i=0; i<=4; i++)
{
if (pattern1.test(string1[i]))
{
document.write(string1[i], " -> match found with fo?d ","<br\>");
}
else
{
document.write(string1[i], " -> match not found with fo?d","<br\>");
}
}
//-->
</script>
</body>
</html>
|
Try this Example online
You can try this example online at - here .
This script gives the following output.
food -> match not found with fo?d fod -> match found with fo?d fd -> match found with fo?d foooood -> match not found with fo?d fud -> match not found with fo?d
Can you think of a practical example of the anchor "?". Assume that you want to search for a string which can be singular or plural. So the regular expression RegExp("expressions?") will match the strings "expression" as well as "expressions".