Given a format string, replace appropriate fields with all combinations of input lists.

combinations.js

function hasValue(x) {
  return x.toString().length > 0;
}

function hasValues(values) {
  for (var i = 0; i < values.length; i += 1) {
    if (values[i].toString().length > 0) {
      return true;
    }
  }
  return false
}

function dropEmptyCells(x) {
  return _.filter(x, hasValue)
}

function cleanAndCross(x) {
  return cross(_.map(_.filter(transpose(x), hasValues), dropEmptyCells))
}

// http://stackoverflow.com/questions/17428587/transposing-a-2d-array-in-javascript
function transpose(array) {
  return _.zip.apply(_, array)
};

// https://gist.github.com/ijy/6094414
function cartesianProductOf() {
    return _.reduce(arguments, function(a, b) {
        return _.flatten(_.map(a, function(x) {
            return _.map(b, function(y) {
                return x.concat([y]);
            });
        }), true);
    }, [ [] ]);
};

function cross(x) {
  return cartesianProductOf.apply(this, x)
}

function contains(a,b) {
  return a.indexOf(b) != -1;
}

/*  ------------------------------------------------
    String -> Array String -> Array String -> String
    ------------------------------------------------
    Given a format string, an array of search strings, and a an array of 
    replacement strings, replace the search strings in the format string.
 */
function multireplace(formatString, searchStrings, replaceStrings) {
    var ret = formatString;
    for (var i = 0; i < searchStrings.length; i += 1) {
        ret = ret.replace(new RegExp(searchStrings[i], 'g'), replaceStrings[i]);
    }
    return ret
}

/*  --------------------------------------------------------------
    String -> Array String -> Array (Array String) -> Array String
    --------------------------------------------------------------
    Given a format string, an array of search strings, and multiple arrays of 
    replacement strings, return new format strings with replacements. 
 */
function formatCombinations(formatString, searchStrings, combinations) {
    return combinations.map(function(replaceStrings){return multireplace(formatString, searchStrings, replaceStrings)})
}

/*  --------------------------------------------------------
    String -> Array (Array String) -> Array String
    --------------------------------------------------------
    Given a format string, and multiple arrays, where the first are target strings, 
    and the rest replacement strings, return new format strings with replacements. 
 */
function generateAllCombinations(string, array) {
  
  function isValidColumnData(x) {
    return hasValue(x[0]) && hasValues(_.tail(x)) && contains(string, x[0])
  }
  
  var columns = _.map(_.filter(transpose(array), isValidColumnData), dropEmptyCells)
  var searchStrings = _.map(columns, _.head)
  var replaceStrings = _.map(columns, _.tail)
  var combinations = cross(replaceStrings)
  return formatCombinations(string, searchStrings, combinations)
}

function numCombinations(string, array) {
  
  function isValidColumnData(x) {
    return hasValue(x[0]) && hasValues(_.tail(x)) && contains(string, x[0])
  }
  
  var columns = _.map(_.filter(transpose(array), isValidColumnData), dropEmptyCells)
  var searchStrings = _.map(columns, _.head)
  var replaceStrings = _.map(columns, _.tail)
  var combinations = cross(replaceStrings)
  return "# Combinations: " + combinations.length
}