题解 | #邮箱字符串判断#

不区分大小写，采用/pattern/i
方法一：
function isAvailableEmail(sEmail) {
var pattern=/^([a-z0-9_])([a-z0-9_])*.?[a-z0-9_]+@[a-z0-9_]+.[a-z]+/i;
return pattern.test(sEmail);
}

方法二：
function isAvailableEmail(sEmail) {
var pattern=/^[a-z0-9][\w.][a-z0-9]@[a-z0-9][\w][a-z0-9]+.[a-z]+/i;
return pattern.test(sEmail);
}