accessing ASP.NET controls in Javascript

Question

I have following Javascript line in my ASP.NET web app:

document.getElementById('<%=myTextBox[0].ClientID %>').value = "test";

how can I access myTextBox elements? for instance I want to change 5th element of this server side array, I want to pass a server side parameter to my function, how can I do it?

for instance:

server side:
ddl.Attributes.Add("onChange", "return OnFoodChange(this,'" + i + "');");


javascript function:
function OnFoodChange(myCmb,myIndex)

using document.getElementById('<%=myTextBox[myIndex].ClientID %>').value = "test"; gives me error, it says that myIndex is not defined, I think because myIndex is used like a server side parameter, how can I solve it?

it is my full JavaScript function:

   function OnFoodChange(myCmb,myIndex) {
               //alert('5');
try{
               var q = document.getElementById('<%= HFFoodPrice.ClientID %>').value.toString();
           var q2 = q.split(';');
           var index = 0;
           //alert(myCmb.selectedIndex.toString());

           //var e = document.getElementById(myCmb);
           var strUser = myCmb.options[myCmb.selectedIndex].value;

           document.getElementById('<%=myTextBox[0].ClientID %>').value = strUser;

           for (var j = 0; j < q2.length; j++) {
               if (q2[j] != '') {
                   var q3 = q2[j].split(',');
                   {

                   }
               }
           }
           }
           catch(err)
           {
           alert(err.message);
           }
       }

can you post some detailed code so that I can help you better. — user1465587
– user1465587, Commented Jul 9, 2012 at 6:03
Are you sure your have a server side array of Textbox called myTextbox? You need to elaborate further on what you are trying to do and how you are trying to do it. Right now there are just bits and pieces of information to go off of. — Kenneth Ito
– Kenneth Ito, Commented Jul 9, 2012 at 6:11

Adil · Accepted Answer · 2012-07-09 06:12:16Z

2

Send this control id of textbox instead of sending index as asp.net control id might not be as you expect,

In Code behind

ddl.Attributes.Add("onChange", "return OnFoodChange(this,'" + myTextBox[i].ClientID + "');");

In HTML

function OnFoodChange(myCmb,myTextBoxId) {
 currentTextBox = document.getElementById(myTextBoxId);
//Your code...
}

answered Jul 9, 2012 at 6:12

Adil

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15 Comments

Adil Over a year ago

Do you assign id to every TextBox you have in myTextBox?

Adil Over a year ago

You have to assign id to TextBox before you add it to array. TextBox t = new TextBox(); t.ID = "SomePrefixIfYouWant" + UniqueNumberMightBeLoopVariable.ToString(); myTextBox.Add(t);

Adil Over a year ago

You have to reflect that thing over here too ddl.Attributes.Add("onChange", "return OnFoodChange(this,'" + i + "');");

Adil Over a year ago

You should not send it, you need to send the with the same naming convention you used for assigning id to TextBoxes with something like "SomePrefixIfYouWant" + UniqueNumberMightBeLoopVariable.ToString();

Adil Over a year ago

okay then view source of page in browser and see what ids you have with textboxes?

|

Rab Khan · Accepted Answer · 2012-07-09 06:09:31Z

1

You are trying to Mix Server side with Client side. it does not work like this. you need to transfer your server array to javascript on server then you will be able access its index on clien side.

answered Jul 9, 2012 at 6:09

Rab Khan

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