How to Pass Values from JavaScript to Java in JSP

How can I pass a JavaScript value to a Java variable in JSP?

<script>
    var jsValue = "Hello, JSP!";
    document.getElementById('hiddenInput').value = jsValue;
    document.getElementById('myForm').submit();
</script>
<form id="myForm" action="yourJspPage.jsp" method="post">
    <input type="hidden" id="hiddenInput" name="jsValue" />
</form>

Passing values from JavaScript to Java in a JSP file can be achieved through form submissions or AJAX calls. This guide outlines a straightforward method using hidden fields in HTML forms to transfer JavaScript values to a Java backend for processing.

<form id="myForm" action="yourJspPage.jsp" method="post">
    <input type="hidden" id="hiddenInput" name="jsValue" />
</form>
<script>
    var jsValue = "Hello from JavaScript!";
    document.getElementById('hiddenInput').value = jsValue;
    document.getElementById('myForm').submit();
</script>

Causes

• The JavaScript variable needs to be sent to the server-side Java code.
• A communication mechanism between client-side JavaScript and server-side Java (the JSP) needs to be established.

Solutions

• Utilize a form element with a hidden input field to store the JavaScript value before submitting it to the server.
• Use AJAX to send the JavaScript value directly to the backend without needing a full page reload.

Mistake: Not including the form action URL correctly.

Solution: Ensure that the action attribute in the form points to the correct JSP page surface.

Mistake: Forgetting to set the method to POST or GET as needed.

Solution: Specify the correct HTTP method in the form's method attribute.