email validation with 20 characters limitation

[sarrafjay]

i want to limit my email input in the registration field with only 20 characters before @domain.com. i can see the regular expression for the validate email in the validation.js file . ie. 

['validate-email', 'Please enter a valid email address. For example johndoe@domain.com.', function (v) {
                //return Validation.get('IsEmpty').test(v) || /\w{1,}[@][\w\-]{1,}([.]([\w\-]{1,})){1,3}$/.test(v)
                //return Validation.get('IsEmpty').test(v) || /^[\!\#$%\*/?|\^\{\}`~&\'\+\-=_a-z0-9][\!\#$%\*/?|\^\{\}`~&\'\+\-=_a-z0-9\.]{1,30}[\!\#$%\*/?|\^\{\}`~&\'\+\-=_a-z0-9]@([a-z0-9_-]{1,30}\.){1,5}[a-z]{2,4}$/i.test(v)
                return Validation.get('IsEmpty').test(v) || /^([a-z0-9,!\#\$%&'\*\+\/=\?\^_`\{\|\}~-]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z0-9,!\#\$%&'\*\+\/=\?\^_`\{\|\}~-]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*@([a-z0-9-]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z0-9-]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*\.(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]){2,})$/i.test(v)
            }],

i m not getting where and how sud i implemnent 20characters limitaition in the above script. any help would be appreciated. 

[AddWebSolution]

Use following code for your purpose:

return Validation.get('IsEmpty').test(v) || /^[\!\#$%\*/?|\^\{\}`~&\'\+\-=_a-z0-9][\!\#$%\*/?|\^\{\}`~&\'\+\-=_a-z0-9\.]{1,20}[\!\#$%\*/?|\^\{\}`~&\'\+\-=_a-z0-9]@([a-z0-9_-]{1,30}\.){1,5}[a-z]{2,4}$/i.test(v)

 Hope this helps, let me know if you face any query/concern regarding this.

[sarrafjay]

thank you very much .. that works like a charm !!  but it is accepting total of 23 characters before @domain.com. i want to limit it to 20 only

also please tell me how do i restrict sample domains. like @domail.com , @test.com , @abc.com ,

[AddWebSolution]

You can check from following URL for Domain Validation in Email

Ref Link:- https://phptipsntricks.wordpress.com/2014/03/07/how-to-check-if-an-email-address-is-valid-in-php/