
How validations are done using javascript ,with example? and interview questions on javASCRIPT.

<html>
<h2>Form Validation</h2>
<script language = "Javascript">
function checkEmail() {
if (/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(form.email.value)){
return true;
}
return false;
}
function checkName(str){
var re = /[^a-zA-Z]/g
if (re.test(str)) return false;
return true;
}
function checkAddress(str){
var re = /[^[a-z][A-Z][0-9]]/g
if(re.test(str)) return false;
return true;
}
function validate(){
var emailID=document.form.email;
var nn=document.form.name;
var add=document.form.address;
if((nn.value==null)||(nn.value=="")){
alert("Please Enter your Name!")
nn.focus();
return false
}
if(checkName(nn.value)==false){
nn.value=""
alert("Invalid Name!");
nn.focus()
return false
}
if((emailID.value==null)||(emailID.value=="")){
alert("Please Enter your Email ID!")
emailID.focus()
return false
}
if (checkEmail(emailID.value)==false){
emailID.value=""
alert("Invalid Email Adderess!");
emailID.focus()
return false
}
if ((add.value==null)||(add.value=="")){
alert("Please Enter your Address!")
add.focus()
return false
}
if (checkAddress(add.value)==false){
add.value=""
alert("Invalid Adderess!");
add.focus()
return false
}
if(document.form.qua.selectedIndex==""){
alert ( "Please select your qualification!" );
return false;
}
return true
}
</script>
<form name="form" method="post" onSubmit="return validate()">
<pre>
Enter Name: <input type="text" name="name" size="30"><br>
Enter an Email Address : <input type="text" name="email" size="30"><br>
Enter Address <textarea name="address" rows="5" cols="23"></textarea><br>
Select Qualification: <select name="qua">
<option value="BTech">BTech</option>
<option value="MBBS">MBBS</option>
<option value="MBA">MBA</option>
<option value="MCA">MCA</option>
</select><br>
<input type="submit" name="Submit" value="Submit">
</pre>
</form>
</html>