Resort a word list by sum of letter value

resort_by_value.js

// 'abc, ghi, def, abd1, g4hi' => 'abc, abd1, def, ghi, g4hi'
// Ignores non-letters in valuation but preserves them in return
function resortByValue(group) {

  function __getWordVal(word) {
    var alphaVals = {
        a: 1, b: 2, c: 3, d: 4, e: 5, f: 6, g: 7, h: 8, i: 9, j: 10, k: 11, l: 12, m: 13, 
        n: 14, o: 15,p: 16, q: 17, r: 18, s: 19, t: 20, u: 21, v: 22, w: 23, x: 24, y: 25, z: 26
    },
    wordSum = 0;

    word.split('').forEach(function (char) {
      wordSum += alphaVals[char] || 0;
    });

    return wordSum;
  }

  function __promote(startPos, endPos, list) {
    var startVal = list[startPos],
        endVal = list[endPos];

    list[startPos] = endVal;
    list[endPos] = startVal;

    return list;
  }

  function __orderWordValList(group) {
    var groupParts = group.constructor === Array ? group : group.split(','),
        prevItemOrder, prevItem, prevItemValue, itemValue;

    groupParts.forEach(function (item, itemOrder) {
      item = item.trimLeft().toLowerCase();

      prevItemOrder = itemOrder - 1 > 0 ? itemOrder - 1 : 0;
      prevItem = groupParts[prevItemOrder];
      prevItemValue = __getWordVal(prevItem);
      itemValue = __getWordVal(item);

      if (itemValue < prevItemValue) {
        groupParts = __promote(itemOrder, prevItemOrder, groupParts);

        __orderWordValList(groupParts);
      }
    });

    return groupParts;
  }

  return __orderWordValList(group).join(',');
}