[javascript] how to set value of a input hidden field through javascript?

I am trying to call the resetyear function and its getting called also but the flow stops at alert("over"), it doesnt tranfer its control to resetmaster. Please suggest me something.

    String flag = "";
    flag = (String) session.getAttribute("flag");
    System.out.println("flag = " + flag);
    if (flag == null) {
        flag = "";
    }
    if (flag.equals("yes")) {
%>   
<script>

   alert(1);
  // resetyear();
    dontreset();
    //document.getElementById("checkyear").value = "1";
    //alert(document.getElementById("checkyear").value);

</script>
<%} else if(flag.equals("no"))
    {%>
<script>
    alert(2);
    //document.getElementById("checkyear").value = "2";
    //alert(document.getElementById("checkyear").value);
    resetyear();
</script>
<%}else{}%>


function resetyear(){

if(confirm("DO YOU WANT TO RESET THE YEAR?"))
{
    alert("hello");
    //document.forms['indexform'].action = "resetmaster";
    //alert(document.forms['indexform'].action);
    //document.forms['indexform'].submit();  
    alert("over");
    form.action = "resetmaster";
    form.submit();
    alert(1);
}

For me it works:

document.getElementById("checkyear").value = "1";
alert(document.getElementById("checkyear").value);

http://jsfiddle.net/zKNqg/

Maybe your JS is not executed and you need to add a function() {} around it all.

It seems to work fine in Google Chrome. Which browser are you using? Here the proof http://jsfiddle.net/CN8XL/

Anyhow you can also access to the input value parameter through the document.FormName.checkyear.value. You have to wrap in the input in a <form> tag like with the proper name attribute, like shown below:

<form name="FormName">
    <input type="hidden" name="checkyear" id="checkyear" value="">
</form>

Have you considered using the jQuery Library? Here are the docs for .val() function.

The first thing I will try - determine if your code with alerts is actually rendered. I see some server "if" code in what you posted, so may be condition to render javascript is not satisfied. So, on the page you working on, right-click -> view source. Try to find the js code there. Please tell us if you found the code on the page.

You need to run your script after the element exists. Move the <input type="hidden" name="checkyear" id="checkyear" value=""> to the beginning.

Your code for setting value for hidden input is correct. Here is the example. Maybe you have some conditions in your if statements that are not allowing your scripts to execute.