I changed the whole code. The edit form's HTML might look a bit like this: The server would set the value of the hidden input with the ID "postID" to the ID of the post in its database before sending the form to the user's browser and would use that information when the form is returned to know which database record to update with modified information. How can I convert a string to boolean in JavaScript? Even though the hidden input cannot be seen at all, its data is still submitted. document.getElementById( "hidElem" ).textContent; for a hidden div element like Previous Topic: Cookie in servlet with example. Our final Js code looks like as written below. if you make just function() {} (without a name for the function) then the function is called onload. Replacing broken pins/legs on a DIP IC package. document.getElementById("someField").type = "hidden"; The above code would change the property type to hidden. if an Element is Hidden You could give your hidden field an id: 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 How to access a hidden input with javascript, How Intuit democratizes AI development across teams through reusability. value Syntax: Example: html Will give you all hidden input fields and filter by those with a specific type="". This must be an integer value 0 or higher. How to set the value of a input hidden field through JavaScript? What does "use strict" do in JavaScript, and what is the reasoning behind it? Making statements based on opinion; back them up with references or personal experience. Find centralized, trusted content and collaborate around the technologies you use most. You can access them by their name attribute - all you need is a reference to the form object. There two possible way to detect the value change on the hidden input field: By using bind () method By using change () method Below examples will illustrate both the methods to detect the change of value in the hidden field. JavaScript get hidden field value by id, by name. Is JavaScript a pass-by-reference or pass-by-value language? Here is the example. Asking for help, clarification, or responding to other answers. Make sure ID attributes should be unique on a web page. Let's look at how we might implement a simple version of the edit form we described earlier (see Tracking edited content), using a hidden input to remember the ID of the record being edited. value javascript Note: The input and change events do not apply to this input type. How to set hidden field value in jQuery [2 Ways] ? The value attribute defines the default value of the hidden input field. This can be used to detect changes in a or