Consider using a prompt like so:
<html>
<script type="text/javascript">
function getValue(){
var retVal = prompt("Enter your name : ", "your name here");
// You can do something like convert it all to lowercase here:
document.write("You have entered : " + retVal.toLowerCase());
}
</script>
Click the following button to see the result:
<form>
<input type="button" value="Click Me" onclick="getValue();" />
</form>
Thus returning modified user input to the user without posting anything or submitting a form. This is just a simple example, but you can take this and apply it to an input field with a button by adding
onclick="functionToDoSomething()"
as an attribute to the button, and having the function get and alter the value of the input field.
solved take html input from user and out modified html back to the user