Pass a javascript variable value into input type hidden value

Question

I would like to assign value of product of two integer numbers into a hidden field already in the html document. I was thinking about getting the value of a javascript variable and then passing it on a input type hidden. I'm having a hard time to explain but this is how it should work:

Script Example

 <script type="text/javascript">  function product(a,b){       return a*b;  }  </script> 

above computes the product and i want the product to be in hidden field.

<input type="hidden" value="[return value from product function]"> 

How is this possible?

Answer 1

You could give your hidden field an id:

<input type="hidden" id="myField" value="" /> 

and then when you want to assign its value:

document.getElementById('myField').value = product(2, 3); 

Make sure that you are performing this assignment after the DOM has been fully loaded, for example in the window.load event.