How to Dynamically Generate Input Form Elements in JavaScript?

Creating Input Form Elements Dynamically

This article delves into a common programming challenge: dynamically creating input form elements based on user input. The goal is to provide a clear and straightforward solution for beginners, using JavaScript.

The Problem

A web page includes a text input field where users can enter a number. Upon clicking a corresponding link, the page should dynamically generate that many input fields for the user to provide additional information. Users can enter a maximum of 10 values.

Understanding the Solution

1. Retrieving User Input:

   • An onclick event handler is applied to the link responsible for generating the input fields.
   • Within the event handler, the value entered in the text input field can be retrieved using document.getElementById().

2. Creating the Container:

   • A container element, such as a div with an id attribute (e.g., "container"), is necessary to hold the dynamically generated input fields.

3. Generating Elements Dynamically:

   • Using document.createElement(), new input elements can be created.
   • Attributes like type and name should be set for each input.
   • appendChild() is used to append each input element to the container.

4. Clearing Previous Elements:

   • To prevent duplicates, any existing child elements within the container should be removed before generating new ones. This can be done using hasChildNodes() and removeChild().

5. Additional Enhancements:

   • You can add elements like line breaks (document.createElement("br")) or text nodes (document.createTextNode()) to improve the layout.

Code Example

The following code snippet demonstrates the implementation of the solution:

    <script type="text/javascript">
        function addFields(){
            // Get number of inputs
            var number = document.getElementById("member").value;

            // Get container
            var container = document.getElementById("container");

            // Clear container
            while (container.hasChildNodes()) {
                container.removeChild(container.lastChild);
            }

            // Generate inputs
            for (i=0;i<number;i++){
                // Text node
                container.appendChild(document.createTextNode("Member " + (i+1)));

                // Input element
                var input = document.createElement("input");
                input.type = "text";
                input.name = "member" + i;
                container.appendChild(input);

                // Line break
                container.appendChild(document.createElement("br"));
            }
        }
    </script>


    <input type="text" id="member" name="member" value="">Number of members: (max. 10)<br>
    <a href="#" id="filldetails" onclick="addFields()">Fill Details</a>
    <div id="container"></div>

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