RegExp object in conjunction with individual regular expression objects you create that contain the regular expression pattern. Creating and using these regular expression objects is described in Chapter 12, "Regular Expression Objects."
Syntax
RegExp.propertyName
Parameters
propertyName is one of the properties listed below.
Properties
Note that six of the RegExp properties have both long and short (Perl-like) names. Both names always refer to the same value. Perl is the programming language from which JavaScript modeled its regular expressions.
Methods
None.
Description
A separate predefined RegExp object is available in each window; that is, each separate thread of JavaScript execution gets its own RegExp object. Because each script runs to completion without interruption in a thread, this assures that different scripts do not overwrite values of the RegExp object.
The predefined RegExp object contains the properties listed above. Except for input and multiline whose values can be preset, property values are set after execution of the regular expression methods exec and test, and the match and replace methods of String.
The script or the browser can preset the input property. If preset and if no string argument is explicitly provided, input's value is used as the string argument to the exec or test methods of the regular expression object. input is set by the browser in the following cases:
input property is cleared after the event handler completes.
The script or the browser can preset the multiline property. When an event handler is called for a TEXTAREA form element, the browser sets multiline to true. multiline is cleared after the event handler completes. This means that, if you've preset multiline to true, it is reset to false after the execution of any event handler.
replace method to switch the words in the string. For the replacement text, the script uses the values of the $1 and $2 properties of the global RegExp object. Note that the RegExp object name is not be prepended to the $ properties when they are passed as the second argument to the replace method.
<SCRIPT LANGUAGE="JavaScript1.2">This displays "Smith, John". Example 2. : In the following example,
re = /(\w+)\s(\w+)/;
str = "John Smith";
newstr=str.replace(re, "$2, $1");
document.write(newstr)
</SCRIPT>
RegExp.input is set by the Change event. In the getInfo function, the exec method uses the value of RegExp.input as its argument. Note that RegExp is prepended to the $ properties.
<HTML>
<SCRIPT LANGUAGE="JavaScript1.2">
function getInfo() {
re = /(\w+)\s(\d+)/;
re.exec();
window.alert(RegExp.$1 + ", your age is " + RegExp.$2);
}
</SCRIPT>
Enter your first name and your age, and then press Enter.
<FORM>
<INPUT TYPE:"TEXT" NAME="NameAge" onChange="getInfo(this);">
</FORM>
</HTML>
Last Updated: 10/22/97 11:48:14