Demonstrate fetching value from hidden fields

HTML

<form action="Test139.htm">
</form>
<button onclick="doTest()" title="Click to retrieve value of hidden field">Test</button>
<p></p>

JavaScript

//click Run icon, then click Test button

function doTest() {
    //create hidden field then append to form
    $("<input>", { type: "hidden", val: "123", name: "testfield" }).hide().appendTo($("form"));
    $("p").text("Value of hidden field is: " + $("input").val());
}