Changing input value using javascript

Question

I've been looking for a reason why this doesn't work, but I can't find one. In my asp.net application I create a a bunch of hidden inputs in c# and then try to modify them in javascript before I call them back to the server.

My c# code:

    hidden3 = new HtmlInputHidden();
    hidden3.ID = "total";
    hidden3.Value = index.ToString();
    this.Controls.Add(hidden3);

my javascript code:

     mod = document.getElementById("total");
     mod.value = newVal;

I can call the value back fine but it doesn't change. I have also added alerts for the original value and then the value after changing values and they both show up fine. However the code is never changed so when I pull the values

To get the value back I am using this;

    HtmlInputHidden hiddenControl = (HtmlInputHidden)FindControl("total");

Maybe you are missing it for a postback. Can you post your page code? Regards — Hector Sanchez
– Hector Sanchez, Commented Jun 3, 2011 at 21:18
How are you trying to "call the value back"? Are you using Request["total"], or are you are dynamically adding back the hidden inputs, then trying to pull the value from that? — Brian Ball
– Brian Ball, Commented Jun 3, 2011 at 21:29

Brian Ball · Accepted Answer · 2011-06-03 21:16:43Z

2

Have you verified that the resulting input tag as the ID of "total"? By default, in Webforms, the actual client-side ID is prefixed with the parent's Id (and a delimiting character); this helps to ensure that IDs are unique. One way to get the real client-side Id is to pull the value from the ClientID property of the control, but you should only look at that value once it has been put in a Controls collection.

answered Jun 3, 2011 at 21:16

Brian Ball

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2 Comments

Akhil Over a year ago

Brian is right. If you are using ASP.NET 4.0, you can set ClientIDMode = "Static", so that the id remains as "total"

user776530 Over a year ago

I was able to get the value using alert(document.getElementById("total").value); but i will try that out anyways

amit_g · Accepted Answer · 2011-06-03 21:17:35Z

1

These controls are dynamically created and they have to be created in each postback. However, these should be built before Page_Load preferably in Page_Init event handler. If these are created in Page_Load, the view state has already been processed and the control can't be set from the posted value.

answered Jun 3, 2011 at 21:17

amit_g

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3 Comments

amit_g Over a year ago

Where are you creating these controls?

user776530 Over a year ago

Page_Load, I create them with a table that i use so I only have to query the database once.

amit_g Over a year ago

Move the create code in Page_Init. Take a look at the article geekswithblogs.net/shahed/archive/2008/06/26/123391.aspx

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