Email Validation

JavaScript for Email Address Validation

In forms when using email ID fields it is a good idea to use client side validation along with your programming language validation. The following example shows how you can validate an email address for a form. This javascript validation code is cross browser compatible (works for all browsers).

Email Validation Example

Example of email validation

Enter an Email Address :

java script code :-

 <script language = "Javascript">
function echeck(str) {

        var at="@"
        var dot="."
        var lat=str.indexOf(at)
        var lstr=str.length
        var ldot=str.indexOf(dot)
        if (str.indexOf(at)==-1){
           alert("Invalid E-mail ID")
           return false
        }

        if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr){
           alert("Invalid E-mail ID")
           return false
        }

        if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr){
            alert("Invalid E-mail ID")
            return false
        }

         if (str.indexOf(at,(lat+1))!=-1){
            alert("Invalid E-mail ID")
            return false
         }

         if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot){
            alert("Invalid E-mail ID")
            return false
         }

         if (str.indexOf(dot,(lat+2))==-1){
            alert("Invalid E-mail ID")
            return false
         }
      
         if (str.indexOf(" ")!=-1){
            alert("Invalid E-mail ID")
            return false
         }

          return true                  
    }

function ValidateForm(){
    var emailID=document.frmSample.txtEmail
  
    if ((emailID.value==null)||(emailID.value=="")){
        alert("Please Enter your Email ID")
        emailID.focus()
        return false
    }
    if (echeck(emailID.value)==false){
        emailID.value=""
        emailID.focus()
        return false
    }
    return true
 }
</script>


Html code :-

<form name="frmSample" method="post" action="#" onSubmit="return ValidateForm()">
                <p>Enter an Email Address :
                  <input type="text" name="txtEmail">
                </p>
                <p>
                  <input type="submit" name="Submit" value="Submit">
                </p>
              </form>

Explanation of the Code

The JavaScript has two functions:

• Function echeck is used to verify if the given value is a possible valid email address. This function simply verifies the following:
1. It makes sure the email address has only one (@) and that it is not at the end or beginning of the email address.
2. It makes sure the email address has atleast one (.) after the @.
3. atleast one (.). It also makes sure that there are no spaces, extra '@'s or a (.) just before or after the @. It also makes sure that there
   
   
• Function ValidateForm is used to make sure that the email field is not blank and that it is a valid email address on form submission.