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JS Regular expression Test () function usage

Source: Internet
Author: User
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Test method

Returns a Boolean value that indicates whether the given regular expression is matched in the string being searched.
Rgexp.test (str)

Parameters

Rgexp
Required option. A regular expression object that contains the regular expression pattern or the available flags.
Str
Required option. The string on which to test the lookup.
Description
The test method checks whether the string matches the given regular expression pattern, returns true if it is, or returns false.

Each regular expression has a lastindex property that records where the last match ended

The code is as follows Copy Code

var re =/^[1-9]d{4,10}$/gi;
var str = "123456";
Alert (Re.test (str)); Returns True

After performing the above test
We can eject

The code is as follows Copy Code

alert (Re.lastindex); Pop up 6

That represents the last time after the 6th character has ended

The next time you call test, the search will continue from the 6th character.

Workaround, set the Lastindex property of the regular expression to 0

The specific code is as follows:

The code is as follows Copy Code

<script type= "Text/javascript" >
var re =/^[1-9]d{4,10}$/gi;
var str = "123456";
Alert (Re.test (str)); Returns True
str = "1234567";
re.lastindex=0;
Alert (Re.test (str)); Returns True
</script>

Example 2

The code is as follows Copy Code

function Testdemo () {
var r, re; Declare a variable.
var s = "I";
re =/i/ig; Creates a regular expression pattern.
document.write (Re.test (s) + "<br/>"); Returns a Boolean result.
document.write (Re.test (s) + "<br/>");
document.write (Re.test (s));
}
Testdemo ();

Output results:

True
False
True


JavaScript forms Validate Email mailboxes, determine whether an input is email, and implement it through regular expressions.
Check email Email

The code is as follows Copy Code

<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 transitional//en" >
<HTML>
<HEAD>
<title>javascript form Verification Email Email </TITLE>
</HEAD>

<BODY>
<script language= "JavaScript" >
function Check () {
var Email=document.getelementbyid ("email"). Value;
var isemail=/^w+ ([-.] w+) *@w+ ([.-]w+) *.w{2,4}$/;
if (email== "") {
Alert ("Please enter your email address!");
return false;
}
if (email.length>25) {
Alert ("Length too long");

return False
}
if (!isemail.test (email)) {
Alert ("Not a Mailbox");
return false;
}

}

</script>
<form method=post action= "" Onsubmit= "return Check ()" >
<input type= "text" name= "email" ><input type= "Submit" >
</FORM>


</BODY>
</HTML>

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

Related Keywords:
email regular expression invert regular expression pcre regular expression examples perl regular expression builder perl regular expression modifiers perl regular expression tutorial perl script regular expression

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