Traveling Animation

JavaScript
1

I am in school and have this assignment to create a fish tank with fish moving across the screen using JS. All the fish are moving left to right except fish #2. I want that to move right to left. I was provided with some code and I had to put it together and add what was missing. I did that and it works fine except I cannot figure out how to make fish #2 move the opposite direction. Any comments on how to change the code for that fish? This is my coding:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

<head>
<title>Fish Tanks</title>

<script type="text/javascript">
<!-- HIDE FROM INCOMPATIBLE BROWSERS

   var fish1Position = 0;
      horizontal = new Array(50);
      var fillPosition = 10;
      for(var i = 0; i < 50; ++i) {
         horizontal[i] = fillPosition;
         fillPosition += 10;
         }
      function fish1Swim() {
        document.getElementById("fish1").style.left = horizontal[fish1Position] + "px";
        ++fish1Position;
        if (fish1Position == 49)
        fish1Position = 0;
       }

   var fish2Position = 0;
      horizontal = new Array(50);
      var fillPosition = 10;
      for(var i = 0; i < 50; ++i) {
         horizontal[i] = fillPosition;
         fillPosition += 10;
         }
      function fish2Swim() {
        document.getElementById("fish2").style.left = horizontal[fish2Position] + "px";
        ++fish2Position;
        if (fish2Position == 49)
        fish2Position = 0;
       }

   var fish3Position = 0;
      horizontal = new Array(50);
      var fillPosition = 10;
      for(var i = 0; i < 50; ++i) {
         horizontal[i] = fillPosition;
         fillPosition += 10;
         }
      function fish3Swim() {
        document.getElementById("fish3").style.left = horizontal[fish3Position] + "px";
        ++fish3Position;
        if (fish3Position == 49)
        fish3Position = 0;
       }

   var fish4Position = 0;
      horizontal = new Array(50);
      var fillPosition = 10;
      for(var i = 0; i < 50; ++i) {
         horizontal[i] = fillPosition;
         fillPosition += 10;
         }
      function fish4Swim() {
        document.getElementById("fish4").style.left = horizontal[fish4Position] + "px";
        ++fish4Position;
        if (fish4Position == 49)
        fish4Position = 0;
       }

   var fish5Position = 0;
      horizontal = new Array(50);
      var fillPosition = 10;
      for(var i = 0; i < 50; ++i) {
         horizontal[i] = fillPosition;
         fillPosition += 10;
         }
      function fish5Swim() {
        document.getElementById("fish5").style.left = horizontal[fish5Position] + "px";
        ++fish5Position;
        if (fish5Position == 49)
        fish5Position = 0;
       }

   function startSwimming() {
      setInterval("fish1Swim()",100);
      setInterval("fish2Swim()",200);
      setInterval("fish3Swim()",130);
      setInterval("fish4Swim()",170);
      setInterval("fish5Swim()",80);
      }

// STOP HIDING FROM INCOMPATIBLE BROWSERS -->
</script>

</head>

<body onload="startSwimming();">

   <p><span id="fish1" style=
   "position:absolute; left:10px; top:10px"><img src="fish1.gif" alt="Image of a fish" /></span></p>

   <p><span id="fish2" style=
   "position:absolute; left:10px; top:100px"><img src="fish2.gif" alt="Image of a fish" /></span></p>

   <p><span id="fish3" style=
   "position:absolute; left:10px; top:210px"><img src="fish3.gif" alt="Image of a fish" /></span></p>

   <p><span id="fish4" style=
   "position:absolute; left:10px; top:300px"><img src="fish4.gif" alt="Image of a fish" /></span></p>

   <p><span id="fish5" style=
   "position:absolute; left:10px; top:390px"><img src="fish5.gif" alt="Image of a fish" /></span></p>

</body>
</html>
2

Instead of adding to the position you need to subtract.

Instead of resetting the position to 0 when it gets to 49 you need to reset the position to 49 when it gets to 0.

3

Thanks you Stephen. I knew it was in that area but was plugging in the wrong info. Works great now. Thanks