如何在JavaScript中验证电子邮件地址？

var string = "hmharsh3@gmail.com"
var exp = /(\w(=?@)\w+\.{1}[a-zA-Z]{2,})/i
alert(exp.test(string))

使用正则表达式：

 /^[a-z][a-zA-Z0-9_.]*(\.[a-zA-Z][a-zA-Z0-9_.]*)?@[a-z][a-zA-Z-0-9]*\.[a-z]+(\.[a-z]+)?$/

例子：

function validateEmail(email) {
    var re = /^[a-z][a-zA-Z0-9_.]*(\.[a-zA-Z][a-zA-Z0-9_.]*)?@[a-z][a-zA-Z-0-9]*\.[a-z]+(\.[a-z]+)?$/;
    return re.test(email);
}

它应该只允许 @、. 和 _ 符号。

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

/^[a-z0-9](?!.*?[^\na-z0-9]{2})[^\s@]+@[^\s@]+\.[^\s@]+[a-z0-9]$/

如果这个解决方案对您有用，请告诉我。 谢谢。

以下是正则表达式验证：

• @符号之前不能有特殊字符
• （-）和（.）不能在@之后放在一起，在@之后不能有特殊字符，@之前必须有2个字符 电子邮件长度应小于128个字符

function validateEmail(email) {
var chrbeforAt = email.substr(0, email.indexOf('@'));
if (!($.trim(email).length > 127)) {
    if (chrbeforAt.length >= 2) {
        var re = /^(([^<>()[\]{}'^?\\.,!|//#%*-+=&;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/;
        //var re = /[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/;
        return re.test(email);
    } else {
        return false;
    }
} else {
    return false;
}
}

vm.validateEmail = '([a-zA-Z0-9_.]{1,})((@[a-zA-Z]{2,})[\\\.]([a-zA-Z]{2}|[a-zA-Z]{3}))';

function validEmail(input=''){
    const emailPatternInput = /^[^@]{1,64}@[^@]{4,253}$/, emailPatternUrl = /^[^@]{1,64}@[a-z][a-z0-9\.-]{3,252}$/i;
    let email, url, valid = false, error, same = false;
    try{
        email = input.trim();
        // handles punycode, etc using browser's own maintained implementation
        url = new URL('http://'+email);
        let urlderived = `${url.username}@${url.hostname}`;
        same = urlderived === email;
        valid = emailPatternInput.test( email );
        if(!valid) throw new Error('invalid email pattern on input:' + email);
        valid = emailPatternUrl.test( urlderived );
        if(!valid) throw new Error('invalid email pattern on url:' + urlderived);
    }catch(err){
        error = err;
    };
    return {email, url, same, valid, error};
}

[
 'user+this@はじめよう.みんな'
, 'stuff@things.eu'
, 'stuff@things'
, 'user+that@host.com'
, 'Jean+François@anydomain.museum','هيا@יאללה'
, '试@例子.测试.مثال.آزمایشی'
, 'not@@really'
, 'no'
].forEach(email=>console.log(validEmail(email), email));

http://docs.closure-library.googlecode.com/git/class_goog_format_EmailAddress.html

goog.format.EmailAddress.isValidAddrSpec("blah@blah.com")

// This is a fairly naive implementation, but it covers 99% of use cases.
// For more details, see http://en.wikipedia.org/wiki/Email_address#Syntax
// TODO(mariakhomenko): we should also be handling i18n domain names as per
// http://en.wikipedia.org/wiki/Internationalized_domain_name

<pre>
**The personal_info part contains the following ASCII characters.
1.Uppercase (A-Z) and lowercase (a-z) English letters.
2.Digits (0-9).
3.Characters ! # $ % & ' * + - / = ? ^ _ ` { | } ~
4.Character . ( period, dot or fullstop) provided that it is not the first or last character and it will not come one after the other.**
</pre>
*Example of valid email id*
<pre>
yoursite@ourearth.com
my.ownsite@ourearth.org
mysite@you.me.net
xxxx@gmail.com
xxxxxx@yahoo.com
</pre>
<pre>
xxxx.ourearth.com [@ is not present] 
xxxx@.com.my [ tld (Top Level domain) can not start with dot "." ]
@you.me.net [ No character before @ ]
xxxx123@gmail.b [ ".b" is not a valid tld ]
xxxx@.org.org [ tld can not start with dot "." ]
.xxxx@mysite.org [ an email should not be start with "." ]
xxxxx()*@gmail.com [ here the regular expression only allows character, digit, underscore and dash ]
xxxx..1234@yahoo.com [double dots are not allowed
</pre>
**javascript mail code**

    function ValidateEmail(inputText)
    {
    var mailformat = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/;
    if(inputText.value.match(mailformat))
    {
    document.form1.text1.focus();
    return true;
    }
    else
    {
    alert("You have entered an invalid email address!");
    document.form1.text1.focus();
    return false;
    }
    }

最佳选择：D（符合RFC标准且没有“过于复杂”的错误）：

function    isMail(mail)
{
    pattuser = /^([A-Z0-9_%+\-!#$&'*\/=?^`{|}~]+\.?)*[A-Z0-9_%+\-!#$&'*\/=?^`{|}~]+$/i;
    pattdomain = /^([A-Z0-9-]+\.?)*[A-Z0-9-]+(\.[A-Z]{2,9})+$/i;

    tab = mail.split("@");
    if (tab.length != 2)
        return false;
    return (pattuser.test(tab[0]) && pattdomain.test(tab[1]));
}