Syntax
var variable = new RegExp(pattern, flags)
The RegExp() object represents a regular expression that is used for pattern matching.
The creation of the object takes pattern and flags parameters.
The pattern is a valid regular expression. The flags are either or both g (global) and i (ignore case).
Properties and Methods of the RegExp() Object
| Property/Method | Description |
| RegExp.$* | Represents multiline |
| RegExp.$& | Represents lastmatch |
| RegExp.$_ | Represents input |
| RegExp.$` | Represents leftContext |
| RegExp.$' | Represents rightContext |
| RegExp.$+ | Represents lastParen |
| RegExp.$1,$2,...$9 | Represents substring of matches |
| compile() | Compiles a regular expression |
| exec() | Executes the search for a match in a specified string |
| global | _Specifies whether to check the expressions against all possible matches |
| ignoreCase | Whether case is ignored or not during a string search |
| input | String that is matched |
| lastIndex | _Specifies the index at which to start matching the next string. |
| lastMatch | Last matched characters |
| lastParen | The last parenthesized substring match |
| leftContext | The substring preceding the most recent match |
| multiline | Specifies whether to search on multiple lines |
| rightContext | The substring following the most recent match |
| source | The string pattern |
| test() | Tests for a string match |
<html>
<body>
<script language="JavaScript">
<!--
function isSSN(str){
// xxx-xx-xxxx
var regexp = /^(\d{9}|\d{3}-\d{2}-\d{4})$/;
return regexp.test(str);
}
function checkInput(){
var valid = true;
var ssn = document.form1.ssn.value;
if (!isSSN (ssn)){
window.alert("Invalid SSN: " + ssn);
valid = false;
}
else{
alert(ssn + " is a valid SSN");
}
}
-->
</script>
<form name="form1">
Enter your SSN:
<input type="text" size="15" name="ssn">
<br><br>
<input type="button" value="Validate SSN" onClick='checkInput()'>
<br>
</form>
</body>
</html>