How to verify email format using JS

This time I will show you how to use JS to verify the E-mail format, and what are the precautions for using JS to verify the E-mail format. The following is a practical case, let's take a look.

I recently worked on a front-end project, which requires that the input data must contain the @ symbol and the period (.). At the same time, @ cannot be the first character of the email address, and there must be at least one period after @.

1: Code

nbsp;html>


<meta>
<title>利用JavaScript验证是否符合电子邮箱地址</title>

<script>
  // 创建第一个函数validate_emil()并包含两个参数
  function validate_email(field, alerttxt) {
    with (field) {
      //利用indexOf() 方法返回某个指定的字符串值在字符串中首次出现的位置--定义一个变量apos将第一次出现的“@”赋值给apos
      apos = value.indexOf("@");
      //利用lastIndexOf() 方法返回一个指定的字符串值最后出现的位置，在一个字符串中的指定位置从后向前搜索--
      //stringObject.lastIndexOf(searchvalue,fromindex)
      //fromindex 可选的整数参数。规定在字符串中开始检索的位置。它的合法取值是 0 到 stringObject.length - 1。如省略该参数，则将从字符串的最后一个字符处开始检索。
      dotpos = value.lastIndexOf(".");
      // 判断符合"@"的位置，或者"."的位置是否在"@"的后面
      if (apos < 1 || dotpos - apos < 2) {
        // 利用alert()弹出一个警告窗来执行alerttxt的操作
        // 邮箱地址不符合
        alert(alerttxt);
        return false;
      } else {
        // 邮箱地址符合
        return true;
      }
    }
  }
  // 创建第二个函数validate_form()并包含一个参数
  function validate_form(thisform) {
    with (thisform) {
      if (validate_email(email, "Not a valid e-mail address!") == false) {
        // 利用focus()将输入焦点移至对象上
        email.focus();
        return false;
      }
    }
  }
</script>

  <!-- onsubmit是一个验证表单功能,为true提交， -->
  

    Email:     

2: Result

The following picture explains The email format you entered is accurate, whether it exists or not is another matter!

# 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!

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