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Hidden value is always null

jssong2000
jssong2000 asked
on
373 Views
Last Modified: 2013-11-14
Hi Expert,

I created a HiddenField control:
 <asp:HiddenField runat="server" ID="hiddenisCheckedout" />


And I set value to the hidden field from code behind:

if (isCheckedout())
{
     hiddenisCheckedout.Value = "true";
}
else
{
     hiddenisCheckedout.Value = "false";
}


And then I retrieve the value in Javascript:
        var isChked = document.getElementById('hiddenisCheckedout');
        alert(isChked);

But isChked is always null. It shoud be the value I setup from code behind. Please help.

Appreciated!!
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Rajkumar GsSoftware Engineer

Commented:
Hi
Try adding  .value
document.getElementById('hiddenisCheckedout').value;
       
Raj
From Mobile
Rajkumar GsSoftware Engineer

Commented:
If not works try

document.getElementById('<%= hiddenisCheckedout.ClientID %>'').value;

Author

Commented:
It does not allow me to do this. Only valueof available on the list when I type "." Thanks!
leakim971Multitechnician
CERTIFIED EXPERT
Distinguished Expert 2019

Commented:
try this :
var isChked = document.getElementById('<%= hiddenisCheckedout.ClientID %>');
alert( isChked ? isChked.value : "field not found" );

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Author

Commented:
field not found

so the hidden field has problem.
leakim971Multitechnician
CERTIFIED EXPERT
Distinguished Expert 2019

Commented:
do a right click on the page in your web browser, choose view source and post it here

Author

Commented:
<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head><title>

</title></head>
<body>
    <form method="post" action="Default.aspx" id="form1">
<div class="aspNetHidden">
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="izwqc5WQZyDCR+BuJMRPJMse5OYwgnLKs8wVFArRTZAwVacizcc/aBGavK5C7Qa7GU74j1XrkyiwlC8OWUN2/iWUAZ4AlUY4IC1lqDL4Ykw=" />
</div>

<div class="aspNetHidden">

	<input type="hidden" name="__EVENTVALIDATION" id="__EVENTVALIDATION" value="Ol14+jgIk+FbIeTSdI5ltslouQ0rO/ZO3WcKopuYsoxYGB+63ej8hyE7uMYBFO6Dirz+VvnpC+wvSgAbgZVSKVEsGJ+TMsdV+pSp41hK2GWbH9cIhnmvNmQTQTIUNnhmSZOTKD1bP8jRIiLUvjMaAA==" />
</div>
               <script type="text/javascript">
                   var isChked = document.getElementById('hiddenisCheckedout');
                   alert(isChked ? isChked.value : "field not found");



                   function getCookie(c_name) {
                       var c_value = document.cookie;
                       var c_start = c_value.indexOf(" " + c_name + "=");
                       if (c_start == -1) {
                           c_start = c_value.indexOf(c_name + "=");
                       }
                       if (c_start == -1) {
                           c_value = null;
                       }
                       else {
                           c_start = c_value.indexOf("=", c_start) + 1;
                           var c_end = c_value.indexOf(";", c_start);
                           if (c_end == -1) {
                               c_end = c_value.length;
                           }
                           c_value = unescape(c_value.substring(c_start, c_end));
                       }
                       return c_value;
                   }
                   function setCookie(c_name, value, exdays) {
                       var exdate = new Date();
                       exdate.setDate(exdate.getDate() + exdays);
                       var c_value = escape(value) + ((exdays == null) ? "" : "; expires=" + exdate.toUTCString());
                       document.cookie = c_name + "=" + c_value;
                   }

                   //alert('test1 = ' + getCookie('test1'));
                   //setCookie('test1', null, 1);
                   //alert('test1 again ==' + getCookie('test1'));


               </script>
    <div>
    
    </div>
        <p>
            Hello</p>
        <p>
            &nbsp;</p>
        <input type="submit" name="Button1" value="Button" id="Button1" />
         <input type="hidden" name="hiddenisCheckedout" id="hiddenisCheckedout" value="false" />
    </form>
</body>
</html>

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leakim971Multitechnician
CERTIFIED EXPERT
Distinguished Expert 2019

Commented:
replace :
      var isChked = document.getElementById('hiddenisCheckedout');
                   alert(isChked ? isChked.value : "field not found");
by :
window.onload = function() {
      var isChked = document.getElementById('hiddenisCheckedout');
                   alert(isChked ? isChked.value : "field not found");
}

or put your script at the end of the page
else you can't get a reference of a field not already present in the page, the html of field is loaded after the script and it's execution

using window.onload wait the complete loading of the page
Multitechnician
CERTIFIED EXPERT
Distinguished Expert 2019
Commented:
This one is on us!
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Author

Commented:
Great job. Appreciated!!

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