The following code won't work if you run it (if you remove the var fedTable it will).

Basically, I need to tap into the declared array var fedTable to do withholding calculations.

I need to first declare where the person stands in the table, and then perform the calculation based off of where they stand.

Code:
<HTML>
<script language="JavaScript">

// Payroll Processing Program by Sprrr - - - - payroll2.html


// Fed Tax Array
var fedTable = new Array(     51,         0,  .15
                                     525,    71.10,  .28
                                    1125,  239.10,  .31
                                    2535,  676.20,  .36
                                   5475, 1734.60, .396);

// Variables
document.writeln('Welcome to the online payroll processing program');
document.writeln();
go_on = 'Y'
empname = prompt('Enter any employee name','');

function do_calc()
{
  if (hours > 40) gross_pay = 40 * payrate + (hours - 40) * payrate * 1.5;
  if (hours <= 40) gross_pay = hours*payrate;
  total_pay = gross_pay*0.0175
}

function do_display()
{
  document.writeln('The Payroll for: ',empname,'<P>');
  document.writeln('Payrate: ',payrate,'<BR>');
  document.writeln('Hours Worked: ',hours,'<BR>');
  document.writeln('Gross Pay: ',gross_pay,'<BR>');
  document.writeln('Total Pay After Withholdings: ',gross_pay - total_pay);
  go_on = prompt('Do you want to process another employee? Y or N','Y');
  if (go_on == 'Y') empname = prompt('Enter any Employee Name','');
}

while ((empname != '') & (go_on == 'Y'))
{
  payrate = prompt('Enter the Employees Payrate','');
  hours   = prompt('Enter the hours worked','');

  // Payroll calculations
  do_calc()

  // Output
  do_display()
}

</script>
</HTML>
The first number in each row (first number on the left) is a money amount. For instance, if the user falls between $51 and $524, they will get their earnings withheld according to the $51 row (flat $0 reduction and .15%).

If they fall between $525 and $1124, they are within the $525 row and get a flat $71.10 reduced and 28% too.

And so on.

Can anyone give me any pointers?

The end product needs to get their total pay and subtract from it the flat/percentage amount in the table correspondingly.