javascript to add 2 numbers in textboxes in asp.net, doesnt work

Question

this is my javascript to get addition of 2 values from 2 textboxes into the third....

its not working...

<script type="text/javascript">

    function calculate(ctrl1, ctrl2, ctrl3) {

        var c1 = document.getElementById(ctrl1);
        var c2 = document.getElementById(ctrl2);
        var c3 = document.getElementById(ctrl3);

        if (c1 != null && c2 != null & c3 != null) {
            c3.value = Number(c1.value) + Number(c2.value);

        }
        document.forms[0].txteanum.focus();

    }    
</script>

in textboxes

<asp:TextBox ID="txtQuantity" runat="server" onblur='javascript:calculate("txtQuantity","txtRate","TxtAmount")'></asp:TextBox>

check my answer here https://stackoverflow.com/a/11624756/1445836

Is the capital "T" in "TxtAmount" a typo? (You have lower-case "t" in the other fields.) If you View Source in the browser are those ids the ones actually produced from the ASP code? — nnnnnn
– nnnnnn, Commented Jul 23, 2012 at 12:21
could you write an else part and put an alert / console.log to find if any of those textboxes are null? — codeandcloud
– codeandcloud, Commented Jul 23, 2012 at 12:26
Your code works for me: jsfiddle.net/r3SvQ so I assume what I mentioned in the previous comment is the problem. Try adding a ClientIDMode="Static" attribute to your inputs... — nnnnnn
– nnnnnn, Commented Jul 23, 2012 at 12:38
See @hasanchuck's answer - you are using server side controls and their IDs may not be what you expect. — EdSF
– EdSF, Commented Jul 23, 2012 at 13:45

Novak · Accepted Answer · 2012-07-23 12:26:49Z

3

Correct: if (c1 != null && c2 != null & c3 != null)

TO: if (c1 != null && c2 != null && c3 != null) Missing &

To commenters: Sorry I never heard of Number(), since I usually don't work with front-end (especially math in front-end), mostly PHP/C#.

Also, c2, c3 are <input>'s ?

edited Jul 23, 2012 at 12:26

answered Jul 23, 2012 at 12:20

Novak

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3 Comments

nnnnnn Over a year ago

Good catch on the &, except that it doesn't actually matter: jsfiddle.net/r3SvQ

codeandcloud Over a year ago

@GuyDavid: +1 on the & catch. Also, it would be better if OP uses ClientIDMode="Static". It might be a case of ID mangling.

nnnnnn Over a year ago

Effectively the operands are converted to numbers such that in practice true & true returns 1 and true & false or other combinations with false return 0. See Bitwise logical operators at MDN.

hasanchuk · Accepted Answer · 2012-07-23 12:34:43Z

2

Maybe You can't get textboxes. Have you tried to give them clientidmode static?

<asp:TextBox ID="txtQuantity" runat="server" onblur='javascript:calculate("txtQuantity","txtRate","TxtAmount")' ClientIDMode="static"></asp:TextBox>

answered Jul 23, 2012 at 12:34

hasanchuk

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Comments

Zoya · Accepted Answer · 2012-07-24 05:38:32Z

here is the java script which worked for me

function Sum() {
                        var text1 = document.getElementById('<%= TextBox1.ClientID %>');
                        var text2 = document.getElementById('<%= TextBox2.ClientID %>');
                        if (text1.value.length == 0 || text2.value.length == 0) {
                                alert('Textbox1 and Textbox2 should not be empty');
                                return;
                        }

                        var x = parseInt(text1.value);
                        var y = parseInt(text2.value);
                        document.getElementById('<%= TextBox3.ClientID %>').value = x +y;
                }

into the textboxes in .aspx page itself

<asp:TextBox ID="TextBox1" runat="server" onblur="Sum()"></asp:TextBox>
<asp:TextBox ID="TextBox2" runat="server" onblur="Sum()"></asp:TextBox>
<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>

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