JS Regular validation format

 functionTest ()       {            vartemp = document.getElementById ("Text1");            //verification of e-mail            varMyreg =/^ ([a-za-z0-9]+[_|\_|\.]?) *[a-za-z0-9][email protected] ([a-za-z0-9]+[_|\_|\.]?) *[a-za-z0-9]+\. [A-za-z] {2,3}$/;            if(!myreg.test (temp.value))           { alert (' hint \ n \ \ Please enter a valid e_mail! ‘); Myreg.focus ();                return false;           }        }        //because the method is the same, write only the relevant regular expressions        //verification of mobile phone numbers (two methods available)        varmobile=/^ ((13[0-9]{1}) |159|153) +\d{8}$/;        varmobile1=/^ (13+\d{9}) | (159+\d{8}) | (153+\d{8}) $/;        //Validation for area code        varPhoneareanum =/^\d{3,4}$/;        //verification of phone numbers        varPhone =/^\d{7,8}$/;

Two. Explaining the relevance
1./^$/this is a generic format.
^ matches the starting position of the input string; $ matches the end position of the input string
2. Enter the functions that need to be implemented.
* Match the preceding sub-expression 0 or more times;
+ Match the preceding subexpression one or more times;
？ Matches the preceding subexpression 0 or one time;
\d matches a numeric character, equivalent to [0-9]

JS Regular validation format