Change value of input on form submit in JavaScript?

Javascript Web Development Object Oriented Programming

To change value of input, use the concept of document. The syntax is as follows −

document.yourFormName.yourTextName.value=anyValue;

Let’s say the following is our input type calling submitForm() on clicking “Submit Form” −

<form name="studentForm" onsubmit="submitForm();">
   <input type="hidden" name="txtInput" value="10000" />
   <input type="submit" value="Submit Form"/>
</form>

The submitForm() function changing the value of input −

function submitForm(){
   document.studentForm.txtInput.value='STUDENT-100';
}

Example

Live Demo

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initialscale=1.0">
<title>Document</title>
<link rel="stylesheet" href="//code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css">
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
<script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"
></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.
css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u"
crossorigin="anonymous">
</head>
<body>
<form name="studentForm" onsubmit="submitForm();">
<input type="hidden" name="txtInput" value="10000" />
<input type="submit" value="Submit Form"/>
</form>
<script>
   function submitForm(){
      document.studentForm.txtInput.value='STUDENT-100';
   }
</script>
</body>
</html>

To run the above program, save the file name “anyName.html(index.html)” and right click on the file. Select the option “Open with Live Server” in VS Code editor.