Get the largest binary gap from a positive integer

get_largest_binary_gap.js

(function(input){

function getLargestBinaryGap(n) {
  var input = (function(){
    if(typeof n !== "number"){
      throw new Error("argument is not a number.")
    }

    if(n < 0){
      throw new Error("argument is less than zero.")
    }

    return {
      toBinary: function(){
        n = (n).toString(2);
        return this
      },
      toGaps: function(gap){
        gap = 0;
        n.split("").map(function(d){
          if (typeof n !== "object") n = [];
          if (d === "1") {
            if (gap) {
              n[n.length] = gap;              
            }
            gap = 0;            
          } else {
            gap++;
          }            
        });
        return this
      },
      getLargest: function(){
        if (!n.length) return 0;
        n.sort();
        return n.pop()
      }
    }
  })();    

  return input
    .toBinary()
    .toGaps()
    .getLargest()
}

return getLargestBinaryGap(input)

})(529)