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Auto-resort numbers in selectable numbered list

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When you have a list of items to sort (say, three items, each with a drop-down from 1-3), this script will (when one of the item drop-downs is changed) automatically change the others to have appropriate numbers. For example, if your list is numbered: 1, 2, 3...and you change the second item to 3, the list will then be numbered 1, 3, 2.

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  1. function changeNumericSequence (objSelectChosen)
  2. {
  3.  
  4.   // ------------------------------------------------------------------------------
  5.  
  6.   // Created:  Jeffrey B. Berthiaume
  7.   // Date:     12 December 2000
  8.   // Version:  1.0
  9.  
  10.   // Description: changeNumericSequence manipulates numbers in a series of dropdown
  11.   //   select lists.  If there are three dropdown select lists (each with the options
  12.   //   of "1", "2", and "3") in a numerical sequence, this function will change the
  13.   //   other select lists as appropriate.
  14.  
  15.   //   Each select list in the html form should have the name "cat_" + a common group
  16.   //   name for the group of select lists + a unique identifier.
  17.  
  18.   //   for example:
  19.  
  20.   //     <select name="cat_1_item_32" onChange="changeNumericSequence (this);">
  21.  
  22.   // Parameter:
  23.   //   objSelectChosen (should be the select object that was just changed)
  24.  
  25.   // Usage example: 
  26.   //   <select name="cat_1_item_32" onChange="changeNumericSequence (this);">
  27.  
  28.   // ------------------------------------------------------------------------------
  29.  
  30.   // find out which group of select lists (category) are being manipulated
  31.   strSelectChosenName = objSelectChosen.name;
  32.   arrSelectChosenName = strSelectChosenName.split ("_");
  33.  
  34.   //   strCategoryName contains the name of the category (i.e. the n in "cat_n")
  35.   strCategoryName = arrSelectChosenName [1];
  36.  
  37.   // find total number of items to manipulate
  38.   intNumItems = objSelectChosen.length;
  39.  
  40.   // store the changed number (new number chosen for this dropdown)
  41.   intChangedItemNumber = objSelectChosen.selectedIndex;
  42.  
  43.   arrItemNumbers = new Array (intNumItems);
  44.   arrSelectNames = new Array (intNumItems);
  45.  
  46.  
  47.   // go through and build array of all numbers in select list
  48.  
  49.   // increment through all select lists in the parent form of objSelectChosen
  50.   // if their name begins with "cat_" + strCategoryName then they belong to this group of categories
  51.  
  52.   intTotalFormElements = objSelectChosen.form.elements.length
  53.   intArrTotal = 0;
  54.   for (i = 0; i < intTotalFormElements; i++)
  55.   {
  56.     strElementName = objSelectChosen.form.elements [i].name;
  57.     arrSelectName = strElementName.split ("_");
  58.     if (strCategoryName == arrSelectName [1])
  59.     {
  60.  
  61.       if (strElementName == strSelectChosenName)
  62.       {
  63.         intChangedItemIndex = intArrTotal;
  64.       }
  65.  
  66.       arrSelectNames [intArrTotal] = strElementName;
  67.       arrItemNumbers [intArrTotal] = objSelectChosen.form.elements [i].selectedIndex;
  68.       intArrTotal = intArrTotal + 1;
  69.     }
  70.  
  71.   }
  72.  
  73.   // calculate the number that is missing
  74.   intMissingNum = -1;
  75.   i = 0;
  76.   while (intMissingNum == -1)
  77.   {
  78.     boolNumFound = -1;
  79.  
  80.     for (i2 = 0; i2 < intNumItems; i2++)
  81.     {
  82.  
  83.       if (arrItemNumbers [i2] == i)
  84.       {
  85.         boolNumFound = 0;
  86.       }
  87.  
  88.     }
  89.  
  90.     if (boolNumFound == -1)
  91.     {
  92.       intMissingNum = i;
  93.     }
  94.  
  95.     i++;
  96.  
  97.   }
  98.  
  99.   // re-order the numbers
  100.  
  101.   // the current item was intMissingNum
  102.   // but now it's intChangedItemNumber
  103.  
  104.  
  105.   if (intMissingNum < intChangedItemNumber)
  106.   {
  107.  
  108.     // find all numbers between (intMissingNum + 1) and intChangedItemNumber 
  109.  
  110.     for (i = 0; i < intNumItems; i++)
  111.     {
  112.  
  113.       num = arrItemNumbers [i];
  114.  
  115.       if ((i != intChangedItemIndex) && (num >= (intMissingNum + 1)) && (num <= intChangedItemNumber))
  116.       {
  117.  
  118.         // decrement their indices by 1
  119.         arrItemNumbers [i] = arrItemNumbers [i] - 1;
  120.  
  121.       }
  122.     }
  123.  
  124.  
  125.   }
  126.   else
  127.   {
  128.  
  129.     // find all numbers between (intChangedItemNumber + 1) and intMissingNum
  130.  
  131.     for (i = 0; i < intNumItems; i++)
  132.     {
  133.  
  134.       num = arrItemNumbers [i];
  135.  
  136.       if ((i != intChangedItemIndex) && (num >= intChangedItemNumber) && (num < intMissingNum))
  137.       {
  138.  
  139.         // increment their indices by 1
  140.         arrItemNumbers [i] = arrItemNumbers [i] + 1;
  141.  
  142.       }
  143.     }
  144.  
  145.   }
  146.  
  147.   // change the selection drop boxes to be the newly ordered numbers
  148.  
  149.   for (i = 0; i < intNumItems; i++)
  150.   {
  151.     eval ("document." + objSelectChosen.form.name + "." + arrSelectNames [i] + ".selectedIndex = " + arrItemNumbers [i] + ";")
  152.   }
  153.  
  154.  
  155. }

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