What are the values of for loop and if statement?

Jun 16 2011 1:47 AM
Hi!

I have written the following program from a book, this program is basically for an exception, first I don't understand the follow of this program, specially the values in for loop and in if statement, secondly the only output is this script and nothing is happening, in Red I am writing what I understand and after the program I have few questions:
 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html><head><title>Exception test</title>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<script language="Javascript">
 function primeTest(n)
{
document.write ("Testing"+n+":")
try{
 if (n<1 || n>20) throw "It's out of range"  //n is less than 1 or greater than 20
 for(var i =2; i <n; ++i)          //I is equal to 2 increment in I till I is less than n
 if (n% i ==0) throw "It's divisible by"+  //n divide by 0 reminder 0, then  "It's divisible by"
document.writeln("It's prime. <br>")  //if 0 then its prime
}
catch(exception){  //otherwise catch
document.writeln(exception+'<br>')  //Write exception
}
}
</script>
<meta content="MSHTML 6.00.2900.6082" name="GENERATOR"></head>
<body>
<p>this script </p>
<script language="javascript">
<!-
for(i=0;i<=21;++i)    //this is comment
{
primeTest(i)
}
-></script>
</body></html>
 Questions:
1-At 1st what is the value of n? Since we have not declared it?
2-The 1st value of I is 2?
Thanks in advance
 
 

Answers (2)