Functions represent metadata as they provide some abstracted behavior to be used by data from the web page, and so the function definitions are generally found in the head of a document. Calling functions is part of the information on the web page and occurs in the body of the document. The following is an example of a web page that prompts the user for values of distance and time and prints out the speed. The program exits when a value of "-1" is entered for the distance.

Sentinel Control loop program using a function to calculate speed 
<html>
<head>
<title>Speed web page.</title>
<script>
function speed(distance, time) {
  return distance / time;
}
</script>
</head>
<body>
<script>
let d = prompt("Enter the distance, -1 to end")
while (d != -1) {
  let t = prompt("Enter the time to travel the distance")
  alert(d / t);
  d = prompt("Enter the distance, or -1 to end")
}
</script>
</body>
</html>

Source: Charles W. Kann III, https://www.oercommons.org/courses/programming-for-the-web-from-soup-to-nuts-implementing-a-complete-gis-web-page-using-html5-css-javascript-node-js-mongodb-and-open-layers/view
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Last modified: Tuesday, 11 October 2022, 5:10 PM