Question

91

Please explain this e-mail validation regular expression:

rated 0 times [ 95] [ 4] / answers: 1 / hits: 15382 / 13 Years ago, mon, july 11, 2011, 12:00:00

I have this script uses regular expressions to check that a form field contains a valid email address.Please explain me from declare

var emailfilter=/^w+[+.w-]*@([w-]+.)*w+[w-]*.([a-z]{2,4}|d+)$/i;

Thank you

Source:

<script type=text/javascript>



/***********************************************

* Email Validation script- © Dynamic Drive (www.dynamicdrive.com)

* This notice must stay intact for legal use.

* Visit http://www.dynamicdrive.com/ for full source code

***********************************************/



var emailfilter=/^w+[+.w-]*@([w-]+.)*w+[w-]*.([a-z]{2,4}|d+)$/i



function checkmail(e){

var returnval=emailfilter.test(e.value)

if (returnval==false){

alert(Please enter a valid email address.)

e.select()

}

return returnval

}



</script>



<form>

<input name=myemail type=text style=width: 270px> <input type=submit onClick=return checkmail(this.form.myemail) value=Submit />



</form>

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donovantyriqn

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3 Years ago

answered 13 Years ago wilson · Accepted Answer

/^w+[+.w-]*@([w-]+.)*w+[w-]*.([a-z]{2,4}|d+)$/i

/ = Begin an expression

^ = The matched string must begin here, and only begin here

w = any word (letters, digits, underscores)

+ = match previous expression at least once, unlimited number of times

[] = match any character inside the brackets, but only match one

+. = match a literal + or .

w = another word

- = match a literal -

* = match the previous expression zero or infinite times

@ = match a literal @ symbol

() = make everything inside the parentheses a group (and make them referencable)

[] = another character set

w- = match any word or a literal -

+ = another 1 to infinity quantifier

. = match another literal .

* = another 0 to infinity quantifier

w+ = match a word at least once

[w-]*. = match a word or a dash at least zero times, followed by a literal .

() = another group

[a-z]{2,4} = match lowercase letters at least 2 times but no more than 4 times

| = or (does not match pipe)

d+ = match at least 1 digit

$ = the end of the string

/ = end an expression

i = test the string in a case i nsensitive manner

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