To implement:

Make a routine to prompt the user for input.

  

<html>
<head>
<title>Input test</title>
<script language="JavaScript">
<!-- Start JavaScript

// Create an infinite loop, get user input, and write to screen
// Analysis

while(true)
	{
	fadeToR = prompt("Enter value for Red between 0 and 255 ('Quit' exits).", "0");
	if(fadeToR == null || fadeToR.toLowerCase() == "quit" || fadeToR > 255 || fadeToR < 0)
		break;
	fadeToG = prompt("Enter value for Green between 0 and 255 ('Quit' exits).", "0");
	if(fadeToG == null || fadeToG.toLowerCase() == "quit" || fadeToG > 255 || fadeToG < 0)
		break;
	fadeToB = prompt("Enter value for Blue between 0 and 255 ('Quit' exits).", "0");
	if(fadeToB == null || fadeToB.toLowerCase() == "quit" || fadeToB > 255 || fadeToB < 0)
		break;
	
	document.writeln(fadeToR + ", " + fadeToG + ", " + fadeToB + "<br>");
	}


// End Script -->
</script>
</head>
<body>

</body>
</html>

 

Execute code or main page