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I am using below regular expression to validate email address.
/^\w+([\.-]?\w+)*@\w+([\.-]?w+)*(\.\w{2,3})+$/
Javascript Code:
var email = '[email protected]';
var pattern = /^\w+([\.-]?\w+)*@\w+([\.-]?w+)*(\.\w{2,3})+$/;
if(pattern.test(email)){
return true;
}
The regex evaluates quickly when I provide the below invalid email:
aseflj#$kajsdfklasjdfklasjdfklasdfjklasdjfaklsdfjaklsdjfaklsfaksdjfkasdasdklfjaskldfjjdkfaklsdfjlak@company.com
(I added #$ in the middle of the name)
However when I try to evaluate this email it takes too much time and the browser hangs.
asefljkajsdfklasjdfklasjdfklasdfjklasdjfaklsdfjaklsdjfaklsfaksdjfkasdasdklfjaskldfjjdkfaklsdfjlak@company.com1
(I added com1 in the end)
I'm sure that the regex is correct but not sure why its taking so much time to evaluate the second example. If I provide an email with shorter length it evaluates quickly. See the below example
[email protected]
Please help me fix the performance issue
988
Additionally, the second string needs to contain a dot, which has an additional 2-3 characters after that. With that in mind, to generally validate an email address in JavaScript via Regular Expressions, we translate the rough sketch into a RegExp : let regex = new RegExp('[a-z0-9]+@[a-z]+\.
Don't use regexes for validating emails, unless you have a good reason not to. Use a verification mail instead. In most cases, a regex that simply checks that the string contains an @ is enough.
Regualr expression is a sequence of character which define a specific pattern and also named as abbreviated regex or regexp and sometimes called a rational expression. we can make regular expression like ( “/ABC/” ,”Ab_123.Cd” ,”abc123. -@&”…)
If you want to check whether the user typed in a valid email address, replace the word boundaries with start-of-string and end-of-string anchors, like this: ^[A-Z0-9. _%+-]+@[A-Z0-9. -]+\. [A-Z]{2,}$.
Your regex runs into catastrophic backtracking. Since [\.-]? in ([\.-]?\w+)* is optional, it makes the group degenerates to (\w+)*, which is a classic case of catastrophic backtracking.
Remove the ? resolves the issue.
I also remove the redundant escape of . inside character class, and changed the regex a bit.
^\w+([.-]\w+)*@\w+([.-]\w+)*\.\w{2,3}$
Do note that many new generic TLDs have more than 3 characters. Even some of the gTLD before the expansion have more than 3 characters, such as .info.
And as it is, the regex also doesn't support internationalized domain name.
92
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