array_plus.js

(function(array_plus) {
  function x_flatten(array, sum) {
    sum = sum || [];
    var y;
    for (var x = array.length-1; x >= 0; x--) {
      y = array[x];
      if ((typeof y) == "object" && y.length) {
        x_flatten(y, sum);
      } else {
        sum.unshift(y);
      }
    }
    return sum;
  }

  function x_intersect(array1, array2) {
    var y, sum, seen;
    sum = [];
    seen = {};
    if (array1.length > array2.length) {
      y = array1;
      array1 = array2
      array2 = y;
    }
    for (var x = array2.length-1; x >= 0; x--) {
      y = array1[x];
      if (y) seen[y] = (seen[y] || 0) + 1;
      y = array2[x];
      if (y) seen[y] = (seen[y] || 0) + 1;
    }
    for (y in seen) {
      if (seen[y] > 1) sum.push(y);
    }
    return sum;
  }

  function x_unique(array) {
    var sum = [], seen = {}, y;
    for (var x = array.length-1; x >= 0; x--) {
      y = array[x];
      if (! seen[y]) {
        seen[y] = true;
        sum.push(y)
      }
    }
    return sum;
  }
  array_plus.flatten   = x_flatten;
  array_plus.intersect = x_intersect;
  array_plus.unique    = x_unique;
})(window.array_plus = {});