Want to add two textbox value in javascript, So that when I leave 2nd textbox , 3rd will give added value of first two

Question

2.00/5 (1 vote)

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This is my javascript code:-

XML

<script language="javascript" type="text/javascript">

            function functn() {
                var a = document.getElementById('TextBox1').value;
                var b = document.getElementById('TextBox2').value;
                if (a == "")
                    a = 0;
               else if (b == "")
                    b = 0;

                var res = parseInt(a) + parseInt(b);
                if (!NaN(res)) {
                    document.getElementById('TextBox3').value = res;
                }

                else
                    document.getElementById('TextBox3').value = 0;
            }

        </script>

        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
        <asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>

Can't figure out where I'm wrong. Need HELP!!

Posted 14-Apr-15 5:27am

Deepak Kanswal Sharma

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Comments

Andy Lanng 14-Apr-15 11:41am

How are you expecting the function to be run?
If it runs then have you debugged the function?
If you have then where is the error?
PS: jQuery will probably come up in many answers. Is that something you've looked into before?

ZurdoDev 14-Apr-15 11:54am

Just debug it and you'll see what the issue is.

Sergey Alexandrovich Kryukov 14-Apr-15 13:04pm

There are apparent problems I can see. Please see my answer.
—SA

ZurdoDev 14-Apr-15 13:28pm

a is being pulled from a textbox so if no value is put in, it will be empty string "". That is perfectly valid.

Sergey Alexandrovich Kryukov 14-Apr-15 15:22pm

Ah, right; I failed to see it. Will remove the answer.
Thank you very much for telling me about my mistake.
—SA

Richard Deeming 14-Apr-15 14:03pm

Are you using a master page? If so, the IDs of those <TextBox> controls won't be correct on the client.

Deepak Kanswal Sharma 15-Apr-15 2:32am

I'm not using master page.

Wombaticus 14-Apr-15 18:38pm

what's with the "else if" ...? Check a, then check b, independently.

Deepak Kanswal Sharma 15-Apr-15 2:32am

You mean:-
if(condition)
and
if(condition)

Wombaticus 15-Apr-15 4:03am

I mean just two separate tests:
if (a=='') {a='0';}
if (b=='') {b='0';}

2 solutions

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Mohibur Rashid · Answer 1 · 2015-04-14T16:43:00

There is several bad thing in your coding.

JavaScript

function functn() {
    //no problem
    var a = document.getElementById('TextBox1').value;
    //no problem
    var b = document.getElementById('TextBox2').value;
    if (a == "")
        a = 0;
//problem
//why:
//if a=="" then next statement do not get verified
//what to do? : remove else
   else if (b == "")
        b = 0;
//no problem
    var res = parseInt(a) + parseInt(b);
    //problem;
    //big problem; 
    //if you check on debugger ">typeof NaN", you will get "number"; NaN is not a function. you are suppose to check isNaN; your problem will be solved, I guess.
    if (!NaN(res)) {
        document.getElementById('TextBox3').value = res;
    }
    else
        document.getElementById('TextBox3').value = 0;
//other than the one compilation error and one logical error everything seems fine. 
}

How to debug: I use three software to debug web related issues
1. Firefox : (ctrl+shift+k)
2. Chrome : (ctrl+shift+j)
3. Internet Explorer(11); occasionally(F12)

so, open, say Chrome, press ctrl+shift+j
and then write, in the newly opened console, functn()
press enter
you will see your function error;

anyway, give it a shot.

Deepak Kanswal Sharma · Answer 2 · 2015-04-15T07:06:00

So I found a solution with the button click event:-

XML

<script language="javascript" type="text/javascript">

            function functn() {
                var a = document.getElementById('TextBox1').value;
                var b = document.getElementById('TextBox2').value;
                if (a == "")
                    a = 0;
                if (b == "")
                    b = 0;

                var res = parseInt(a) + parseInt(b);
                //if (!NaN(res))
                {
                    document.getElementById('TextBox3').value = res;
                }


            }

        </script>

        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
        <button id="Button7" value="Click" onclick="functn()">Click</button>
        <asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>

But I want no buttons.

What I want is, as soon as I leave the 2nd textbox, the 3rd textbox gets the sum automatically.

Want to add two textbox value in javascript, So that when I leave 2nd textbox , 3rd will give added value of first two

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