How to Calculate GridView Textbox Values using Javascript

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I Have GridView Columns of Product(Label), Quantity(ASPTextbox), Rate(ASPTextbox) and Amount(Label), whenever i change rate or quantity i want to calculate amount(qty*rate) of product using javascript.

JavaScript

<script type="text/javascript">
        function startCalc() {
            var rate = parseFloat(document.getElementById('<%=gv1.FindControl("txtrate").ClientID%>').value);
            var qty = parseFloat(document.getElementById('<%=gv1.FindControl("txtqty").ClientID%>').value);
            var totalamount = rate * qty;
            document.getElementById('<%=gv1.FindControl("lblamt").ClientID%>').value = totalamount;
        }
    </script>

I am getting an error at var rate = parseFloat(document.getElementById('<%=gv1.FindControl("txtrate").ClientID%>').value); of object reference not set an instance of an object
Please Help Me

Thanks In Advance

Posted 28-Apr-15 20:16pm

Ravi Sargam

Updated 8-Oct-21 4:16am

v5

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Comments

Karthik_Mahalingam 29-Apr-15 2:28am

what you have tried ?
post your code

Ravi Sargam 29-Apr-15 2:42am

please check above code

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 29-Apr-15 6:15am

gv1.FindControl("txtrate") -> There will be many TextBoxes on the GridView, may be one on each row. Which one you want?

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Santhosh Babu Mahimairaj · Answer 1 · 2015-04-29T01:52:00

Hello Ravi,

Good Day !!!

We may have n number of rows in Gridview we should mention the row index t find the text box value

Modify your script like this it will work