Nodejs Array Combination combinations()

Method Source Code

Array.prototype.combinations = function() {
   var array = this;
   var result = [];
   for(var i = 0; i < array.length; i++) {
      for (var j = i+1; j < array.length; j++) {
         if (i != j) {
            result.push( [array[i],array[j]] );
         }//from w w  w  .j a v a2  s . c om
      }
   }
   return result;
}

Related

1. combinationsOf(k)

   Array.prototype.combinationsOf = function(k) {
     var result = [];
     if (k < 1) return result;
     if (k > this.length) return result;
     if (k == this.length) return this.slice(0);
     var indices = new Array(k), n = this.length;
     var total = n.factorial() / ((n - k).factorial() * k.factorial());
     indices.length.times(function(i) { indices[i] = i });
     result.push(this.valuesAt(indices));
   ...