<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
<style type="text/css">
*{
font-family: cursive;
}
</style>
<script type="text/javascript">
function validate()
{
var a = document.getElementById("a");
var b = document.getElementById("b");
var valid = true;
if(a.value.length<=0 || b.value.length<=0)
{
alert("Don't leave the field empty!");
valid = false;
}
else{
if(!IsNumeric(a.value) || !IsNumeric(b.value))
alert("Enter a number");
valid = false;
}
return valid;
};
</script>
</head>
<body bgcolor="#CDCDCC" font-family="cursive" font-size="20px;" font-weight="bold">
<h2>Wele <%=request.getParameter("uname")%>! Enter the numbers and the operation that you want to perform: </h2>
<form font-size="75px;" action ="serv" method="get" onsubmit="return validate();" >
<hr/>
Enter the 1st number: <input type="text" name="a" /><br/>
Enter the 2st number: <input type="text" name="b" /><br/><br/>
<label>Add</label><input type="radio" name="option" value="Add" /><br/>
<label>Subtract</label><input type="radio" name="option" value="Subtract"/><br/>
<label>Multiply</label><input type="radio" name="option" value="Multiply"/><br/>
<label>Divide</label><input type="radio" name="option" value="Divide" /><br/>
<input type="submit" value="Submit" />
</form>
</body>
This is my JSP and I've written a JavaScript function validate() that validates the user input against blank space and String.
My problem is that when i click on the submit button, for correct integer input, it is working. If an invalid input is given, i get a blank page. Can someone help me out with what the problem is and what is that i should modify? Thanks.
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
<style type="text/css">
*{
font-family: cursive;
}
</style>
<script type="text/javascript">
function validate()
{
var a = document.getElementById("a");
var b = document.getElementById("b");
var valid = true;
if(a.value.length<=0 || b.value.length<=0)
{
alert("Don't leave the field empty!");
valid = false;
}
else{
if(!IsNumeric(a.value) || !IsNumeric(b.value))
alert("Enter a number");
valid = false;
}
return valid;
};
</script>
</head>
<body bgcolor="#CDCDCC" font-family="cursive" font-size="20px;" font-weight="bold">
<h2>Wele <%=request.getParameter("uname")%>! Enter the numbers and the operation that you want to perform: </h2>
<form font-size="75px;" action ="serv" method="get" onsubmit="return validate();" >
<hr/>
Enter the 1st number: <input type="text" name="a" /><br/>
Enter the 2st number: <input type="text" name="b" /><br/><br/>
<label>Add</label><input type="radio" name="option" value="Add" /><br/>
<label>Subtract</label><input type="radio" name="option" value="Subtract"/><br/>
<label>Multiply</label><input type="radio" name="option" value="Multiply"/><br/>
<label>Divide</label><input type="radio" name="option" value="Divide" /><br/>
<input type="submit" value="Submit" />
</form>
</body>
This is my JSP and I've written a JavaScript function validate() that validates the user input against blank space and String.
My problem is that when i click on the submit button, for correct integer input, it is working. If an invalid input is given, i get a blank page. Can someone help me out with what the problem is and what is that i should modify? Thanks.
2 Answers
Reset to default 5In you javascript you are checking via ID but there is no ID for input fields.
<input type="text" name="a" id ="a"/>
<input type="text" name="b" id="b" />
to check if a input is string or not use isNAN() like the following way
if(isNaN(a) || isNaN(b)){
alert("enter a number");}
Following is the plete working example
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
<style type="text/css">
*{
font-family: cursive;
}
</style>
<script type="text/javascript">
function validate()
{
var a = document.getElementById("a");
var b = document.getElementById("b");
var c = document.getElementById("a").value;
var d = document.getElementById("b").value;
var valid = true;
if(a.value.length<=0 || b.value.length<=0)
{
alert("Don't leave the field empty!");
valid = false;
}
else{
if(isNaN(c) || isNaN(d)){
alert("Enter a number");
valid = false;}
}
return valid;
};
</script>
</head>
<body bgcolor="#CDCDCC" font-family="cursive" font-size="20px;" font-weight="bold">
<h2>Wele <%=request.getParameter("uname")%>! Enter the numbers and the operation that you want to perform: </h2>
<form font-size="75px;" action ="serv" method="get" onsubmit="return validate();" >
<hr/>
Enter the 1st number: <input type="text" name="a" id="a" /><br/>
Enter the 2st number: <input type="text" name="b" id="b" /><br/><br/>
<label>Add</label><input type="radio" name="option" value="Add" /><br/>
<label>Subtract</label><input type="radio" name="option" value="Subtract"/><br/>
<label>Multiply</label><input type="radio" name="option" value="Multiply"/><br/>
<label>Divide</label><input type="radio" name="option" value="Divide" /><br/>
<input type="submit" value="Submit" />
</form>
</body>
Correct me if I'm wrong but your javascript function is looking for 'a' and 'b' IDs And you don't have such... your input elements got names. add ids attributes...