search

Home >Web Front-end >JS Tutorial >Use regular expressions to filter email addresses/email addresses

Use regular expressions to filter email addresses/email addresses

php中世界最好的语言
php中世界最好的语言Original
2018-05-24 10:13:1611333browse

This time I will bring you the regular expressionsto filter email mailboxes/email addresses and the precautionsto use regular expressions to filter email mailboxes/email addresses. The following are Let’s take a look at practical cases.

When doing user registration, regular expressions for email/email addresses are often used. This article lists several solutions. You can choose the most suitable solution according to your project situation

In short

When registering users, email is often used /Regular expression for email address. This article lists several options. You can choose the most suitable option according to your project situation.

Use regular expressions to filter email addresses/email addresses

Option 1 (Commonly used)

The rules are defined as follows:

  • in capital letters It starts with letters [A-Z], lowercase letters [a-z], numbers [0-9], underscore [_], minus sign [-] and period [.], and needs to be repeated one or more times [+].

  • The @ symbol must be included in the middle.

  • @After that, you need to connect uppercase letters [A-Z], lowercase letters [a-z], numbers [0-9], underscore [_], minus sign [-] and dot [ .], and needs to be repeated one or more times [+].

  • must end with a period [.] connecting 2 to 4 digits of uppercase and lowercase letters [A-Za-z]{2,4}.

Use the above rules to give the following regular expression: 

var pattern = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;

Complete test code

<!DOCTYPE HTML>
<html>
<head>
  <meta charset="utf-8">
  <title>邮箱/邮件地址的正则表达式及分析(JavaScript，email，regex)</title>
</head>
<body>
<p id="main"></p>
<script>
  var pattern = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
  w("pattern.test(&#39;cn42du@163.com&#39;) = "+pattern.test(&#39;cn42du@163.com&#39;)+";");
  w("pattern.test(&#39;ifat3@sina.com.cn&#39;) = "+pattern.test(&#39;ifat3@sina.com.cn&#39;)+";");
  w("pattern.test(&#39;ifat3.it@163.com&#39;) = "+pattern.test(&#39;ifat3.it@163.com&#39;)+";");
  w("pattern.test(&#39;ifat3_-.@42du.cn&#39;) = "+pattern.test(&#39;ifat3_-.@42du.cn&#39;)+";");
  w("pattern.test(&#39;ifat3@42du.online&#39;) = "+pattern.test(&#39;ifat3@42du.online&#39;)+";");
  w("pattern.test(&#39;毛三胖@42du.cn&#39;) = "+pattern.test(&#39;毛三胖@42du.cn&#39;)+";");
  function w(val) {
    document.getElementById("main").innerHTML += val +"<br />";
  }
</script>
</body>
</html>

Test result: 

pattern.test(&#39;cn42du@163.com&#39;) = true;
pattern.test(&#39;ifat3@sina.com.cn&#39;) = true;
pattern.test(&#39;ifat3.it@163.com&#39;) = true;
pattern.test(&#39;ifat3_-.@42du.cn&#39;) = true;
pattern.test(&#39;ifat3@42du.online&#39;) = false;
pattern.test(&#39;毛三胖@42du.cn&#39;) = false;
pattern.test(&#39;cn42du@163.com&#39;) = true;
pattern.test(&#39;ifat3@sina.com.cn&#39;) = true;
pattern.test(&#39;ifat3.it@163.com&#39;) = true;
pattern.test(&#39;ifat3_-.@42du.cn&#39;) = true;
pattern.test(&#39;ifat3@42du.online&#39;) = false;
pattern.test(&#39;毛三胖@42du.cn&#39;) = false;

Description of Scheme 1

Scheme 1 is the most commonly used email regular expression verification scheme and is also suitable for most application scenarios. As can be seen from the above test, this expression does not support domain names ending in .online and .store. If you need to be compatible with this type of domain name (more than 4 digits), just adjust the restriction part at the end of the regular expression {2,4} (for example: {2,8}). Another problem is that email usernames cannot include Chinese characters.

Option 2 (revised option 1)

The rules are supplemented as follows:

  • The user name can include Chinese [\u4e00- \u9fa5]

  • The end of the domain name can be up to 8 digits{2,8}

  • The updated regular expression is as follows:

var pattern = /^([A-Za-z0-9_\-\.\u4e00-\u9fa5])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,8})$/;

Complete test code

<!DOCTYPE HTML>
<html>
<head>
  <meta charset="utf-8">
  <title>邮箱/邮件地址的正则表达式及分析(JavaScript，email，regex)</title>
</head>
<body>
<p id="main"></p>
<script>
  var pattern = /^([A-Za-z0-9_\-\.\u4e00-\u9fa5])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,8})$/;
  w("pattern.test(&#39;cn42du@163.com&#39;) = "+pattern.test(&#39;cn42du@163.com&#39;)+";");
  w("pattern.test(&#39;ifat3@sina.com.cn&#39;) = "+pattern.test(&#39;ifat3@sina.com.cn&#39;)+";");
  w("pattern.test(&#39;ifat3.it@163.com&#39;) = "+pattern.test(&#39;ifat3.it@163.com&#39;)+";");
  w("pattern.test(&#39;ifat3_-.@42du.cn&#39;) = "+pattern.test(&#39;ifat3_-.@42du.cn&#39;)+";");
  w("pattern.test(&#39;ifat3@42du.online&#39;) = "+pattern.test(&#39;ifat3@42du.online&#39;)+";");
  w("pattern.test(&#39;毛三胖@42du.cn&#39;) = "+pattern.test(&#39;毛三胖@42du.cn&#39;)+";");
  function w(val) {
    document.getElementById("main").innerHTML += val +"<br />";
  }
</script>
</body>
</html>

Test result: 

pattern.test(&#39;cn42du@163.com&#39;) = true;
pattern.test(&#39;ifat3@sina.com.cn&#39;) = true;
pattern.test(&#39;ifat3.it@163.com&#39;) = true;
pattern.test(&#39;ifat3_-.@42du.cn&#39;) = true;
pattern.test(&#39;ifat3@42du.online&#39;) = true;
pattern.test(&#39;毛三胖@42du.cn&#39;) = true;

Option 3 (safety)

On mobile phone Before the verification code appeared, email verification was almost the only condition to ensure the uniqueness of the user. The emergence of temporary mailboxes (also called 10-minute mailboxes or disposable mailboxes) makes the mechanism of mailbox verification and account activation meaningless. The addresses of temporary email addresses are not enumerable. We can only use a whitelist to allow only a limited number of email domain names to pass verification.

According to the following supplementary rules in Option 1:

The email domain name can only be 163.com, qq.com or 42du.cn.
The regular expression is given as follows: 

var pattern = /^([A-Za-z0-9_\-\.])+\@(163.com|qq.com|42du.cn)$/;

Complete test code

<!DOCTYPE HTML>
<html>
<head>
  <meta charset="utf-8">
  <title>邮箱/邮件地址的正则表达式及分析(JavaScript，email，regex)</title>
</head>
<body>
<p id="main"></p>
<script>
  var pattern = /^([A-Za-z0-9_\-\.])+\@(163.com|qq.com|42du.cn)$/;
  w("pattern.test(&#39;cn42du@163.com&#39;) = "+pattern.test(&#39;cn42du@163.com&#39;)+";");
  w("pattern.test(&#39;ifat3@sina.com.cn&#39;) = "+pattern.test(&#39;ifat3@sina.com.cn&#39;)+";");
  w("pattern.test(&#39;ifat3.it@163.com&#39;) = "+pattern.test(&#39;ifat3.it@163.com&#39;)+";");
  w("pattern.test(&#39;ifat3_-.@42du.cn&#39;) = "+pattern.test(&#39;ifat3_-.@42du.cn&#39;)+";");
  w("pattern.test(&#39;ifat3@42du.online&#39;) = "+pattern.test(&#39;ifat3@42du.online&#39;)+";");
  w("pattern.test(&#39;毛三胖dd@42du.cn&#39;) = "+pattern.test(&#39;毛三胖@42du.cn&#39;)+";");
  function w(val) {
    document.getElementById("main").innerHTML += val +"<br />";
  }
</script>
</body>
</html>

Test result: 

pattern.test(&#39;cn42du@163.com&#39;) = true;
pattern.test(&#39;ifat3@sina.com.cn&#39;) = false;
pattern.test(&#39;ifat3.it@163.com&#39;) = true;
pattern.test(&#39;ifat3_-.@42du.cn&#39;) = true;
pattern.test(&#39;ifat3@42du.online&#39;) = false;
pattern.test(&#39;毛三胖dd@42du.cn&#39;) = false;

Although scheme 3 verification can ensure security, if the whitelist Too long will cause the pattern string to be too long. At this time, you can write the email domain name whitelist as an array, use regular expressions for preliminary verification, and use the whitelist for secondary verification of the domain name.

The email verification function is now given as follows: 

var isEmail = function (val) {
  var pattern = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
  var domains= ["qq.com","163.com","vip.163.com","263.net","yeah.net","sohu.com","sina.cn","sina.com","eyou.com","gmail.com","hotmail.com","42du.cn"];
  if(pattern.test(val)) {
    var domain = val.substring(val.indexOf("@")+1);
    for(var i = 0; i< domains.length; i++) {
      if(domain == domains[i]) {
        return true;
      }
    }
  }
  return false;
}
// 输出 true
isEmail(cn42du@163.com);

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

Recommended reading:

How to use Vue.js custom events to perform form input components

Vue uses the following table to modify the array What to do when the page does not render

The above is the detailed content of Use regular expressions to filter email addresses/email addresses. For more information, please follow other related articles on the PHP Chinese website!

Statement：
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Previous article：Example analysis on functions such as full selection and inverse selection of shopping cart checkbox in VueNext article：Example analysis on functions such as full selection and inverse selection of shopping cart checkbox in Vue

Related articles

See more