javascript - Performance issue while evaluating email address with a regular expression -

i using below regular expression validate email address.

/^\w+([\.-]?\w+)*@\w+([\.-]?w+)*(\.\w{2,3})+$/ 

javascript code:

var email = 'myname@company.com'  var pattern = /^\w+([\.-]?\w+)*@\w+([\.-]?w+)*(\.\w{2,3})+$/  if(pattern.test(email)){ return true; } 

above regular expression evaluates email address when provide below invalid email address.(i have added #$ in middle of name)

aseflj#$kajsdfklasjdfklasjdfklasdfjklasdjfaklsdfjaklsdjfaklsfaksdjfkasdasdklfjaskldfjjdkfaklsdfjlak@company.com

but when try evaluate below email address takes , browser gets hanged. (i have given com1 in end)

asefljkajsdfklasjdfklasjdfklasdfjklasdjfaklsdfjaklsdjfaklsfaksdjfkasdasdklfjaskldfjjdkfaklsdfjlak@company.com1

i sure regular expression correct not sure why taking time evaluate second example. if provide email address shorter length evaluates quickly. see below example

dfjjdkfaklsdfjlak@company.com1

kindly me fix performance issue.

your regex runs catastrophic backtracking. since [\.-]? in ([\.-]?\w+)* optional, makes group degenerates (\w+)*, classic case of catastrophic backtracking.

remove ? resolves issue.

i remove redundant escape of . inside character class, , changed regex bit.

^\w+([.-]\w+)*@\w+([.-]\w+)*\.\w{2,3}$ 

do note many new generic tlds have more 3 characters. of gtld before expansion have more 3 characters, such .info.

and is, regex doesn't support internationalized domain name.