Help with Javascript in JSP page

Question

I have a JSP which gets a value called sum from the DB...

String sum= request.getAttribute("s").toString();
int s = Integer.parseInt(sum);

I have a field in a form called weight who's value cannot exceed sum.

So on clicking submit i'm running a function called validate. Which would check if field is greater than or equal to sum but it keeps giving me the warning all the time.

<script type="text/javascript">
function validate()
{
    var x= document.getElementById("s");
    if(document.getElementById("weight").value>x)
    {
        alert("Weight exceeds maximum limit...!!!");
        return false;
    }
    return true;
}   
</script>

Would appreciate the help..

Just curious if you're doing things the right way: does validation also work if you turn off JavaScript in your browser? (i.e. you're also doing exactly the same validation in the server side). If not, you've got something to think about :) — BalusC
– BalusC, Commented Sep 4, 2011 at 15:38
Yes i'm doing the validation on the server side aswell.... Thanks :D — John
– John, Commented Sep 6, 2011 at 6:33

Matt Ball · Accepted Answer · 2011-09-04 13:54:09Z

1

This has nothing to do with JSP. You need to parse the values into numbers using parseInt() or parseFloat() before comparing. This is because the .value attribute is always a string. You are also comparing an element's value with an element, which does not make sense.

Try this:

function validate()
{
    var weight = parseFloat(document.getElementById("weight").value),
        maxWeight = parseInt(document.getElementById("s").value, 10);
    if(weight > maxWeight)
    {
        alert("Weight exceeds maximum limit...!!!");
        return false;
    }
    return true;
}

answered Sep 4, 2011 at 13:54

Matt Ball

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7 Comments

John Over a year ago

it still excepts value's greater than weight

Matt Ball Over a year ago

Is there an HTML element in the page with ID s? What is its value?

John Over a year ago

Matt Ball Over a year ago

I didn't ask about an element with ID weight, I asked about an element with ID s.

Matt Ball Over a year ago

You need to make it accessible to JavaScript, then, as in @medopal's answer. Java runs on the server, JavaScript runs in the browser. There's no magic to make the two "see" each other.

|

mohdajami · Accepted Answer · 2011-09-04 13:56:31Z

1

s is a Java variable so you cannot reference it through document.

Try something like:

var x = <%=Integer.parseInt(sum); %>
if (document.getElem...

answered Sep 4, 2011 at 13:56

mohdajami

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