Java Script Basics

Java Script validation:

String length validation:

This Tag Validate the String length by property of (“str.length”)

JavaScript validation is not secure as anybody can change what your script does in the browser. Using it for enhancing the visual experience is ok though.

Code :

var textBox = document.getElementById("myTextBox");

var textLength = textBox.value.length;

if(textLength > 5)

{

    //red

    textBox.style.backgroundColor = "#FF0000";

}

else

{

    //green

    textBox.style.backgroundColor = "#00FF00";

    // alert(“Something”);

}

Here the Code for Change the Color of text box , here We can add the Alert box too..

E-Mail Validation :

The function below checks if the content has the general syntax of an email.

This means that the input data must contain an @ sign and at least one dot (.). Also, the @ must not be the first character of the email address, and the last dot must be present after the @ sign, and minimum 2 characters before the end:

Code:

function validateForm()
{
var x=document.forms["myForm"]["email"].value;
var atpos=x.indexOf("@");
var dotpos=x.lastIndexOf(".");
if (atpos<1 || dotpos<atpos+2 || dotpos+2>=x.length)
  {
  alert("Not a valid e-mail address");
  return false;
  }
}