help with script

[phoenix1215]

I need to make a script that will calculate the moon phase based on the moon's position... it's for an online game

here's what I've got - members locate the position by viewing the page source and it's always a number

then they would enter that number into an input box and submit it, which then would figure the answer one of 2 ways:

if the number is >=180, it subtracts 157.5 and then divides by 22.5, rounds the number and that's the answer

if the number is <180, it adds 202.5 and then divides by 22.5, rounds the number and that's the answer

I've posted on several different coding forums to try to get help: I wrote a script once before with lots of help from other people but I didn't know half of what I was doing or even what it all meant, just that it did what I wanted it to...

so on one forum someone posted this:

function calculate(position) {
  var phase;
  position = parseFloat(position);
  if (position > 180) {
     phase = Math.round((position - 157.5) / 22.5);
     provideAnswer(phase);
     }
  else if (position < 180) {
     phase = Math.round((position - 202.5) / 22.5);
     provideAnswer(phase);
     }
  else {
    var text = document.createTextNode("You must enter a number!");
    document.getElementsByTagName("div")[0].appendChild(text);
    }
  }
 
function provideAnswer(phase) {
  // Do Something
  }

and the html code was

<div>
  <input type="text" id="position">
  <input type="submit" onclick="calculate('position');">
</div>

all that did was write You must enter a number! over and over again

then he said that the code was wrong and that calculate('position') should be calculate(document.getElementById('position').valu e) but when I changed the values in both the script and the html it just disabled it completely

please help?

[acoder]

Try

var pos = parseFloat(position);

then replace position in the if statements with pos.

You should also check for invalid numbers using isNaN(pos).