node.is中的电子邮件验证编码

Question

这是电子邮件验证代码。

我只知道做例5，邮件长度必须超过5个字符串，否则，会变成错误，提醒人们重新写邮件。

我不知道如何根据邮件要求编写示例2-4。请给我一些建议。非常感谢!

function validateEmail(email) {
console.log(email)
// email requirements as below:
// email length >= 5 character
// @ cannot be the first character
// @ must before .
// . cannot be the last character

// example 
// 1. [e-mail] < return true
// 2. @a.com < return false, throw TypeError: invalid email address
// 3. a.b@com < return false, throw TypeError: invalid email address
// 4. [e-mail]. < return false, throw TypeError: invalid email address
// 5. a@a.c < return false, throw TypeError: e-mail address too short
// 6. a@.com < return ture

// example 5, email length >= 5 character
if(email.length<5) {
throw new TypeError(`e-mail address too short`)
}
// example 4,  . cannot be the last character

}

// example 1,6
return true
function newFunction() {
return "'"
}

Answer 1

您可以遵循此REGAX来验证电子邮件。请检查

const emailToValidate = '[e-mail]';
const emailRegexp = /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/;
console.log(emailRegexp.test(emailToValidate));

感谢