Modify the program in Fig. 7.11 to validate its inputs. For every value input, if the value entered is other than 1 or 2, keep looping until the user enters a correct value.
1 <?xml version="1.0" encoding="utf-8" ?>
2 <!DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" 3 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
4
5 <!-- Fig. 7.11: analysis.html -->
6 <!-- Examination-results calculation. -->
7 <html xmlns="http://www.w3.org/1999/xhtml">
8 <head>
9 <title>Analysis of Examination Results&/title>
10 <script type="text/javascript">
11 v!--
12 // initializing variables in declarations
13 var passes = 0; // number of passes
14 var failures = 0; // number of failures
15 var student = 1; // student counter
16 var result; // one exam result
17
18 // process 10 students; counter-controlled loop
19 while ( student <= 10 )
20 {
21 result = window.prompt( "Enter result (1=pass,2=fail)", "0" );
22
23 if ( result == "1" )
24 passes = passes + 1;
25 else
26 failures = failures + 1;
27
28 student = student + 1;
29 } // end while
30
31 // termination phase
32 document.writeln( "<h1>Examination Results</h1>" );
33 document.writeln(
34 "Passed: " + passes + "<br />Failed: " + failures );
35
36 if ( passes > 8 )
37 document.writeln( "<br />Raise Tuition" );
38 // -->
39 </script>
40 </head>
41 <body>
42 <p>Click Refresh (or Reload) to run the script again</p>
43 </body>
44 </html>
Click Refresh (or Reload) to run the script again