Simpe test on how to strip out duplications from array in Javascript

filterDuplicated.js

var _ = require('underscore');
var ObjectID = require('mongodb').ObjectID;

var duplicatedIds = [];
var lengthOfDuplicatedIds = 10;
for (var i = 0; i < lengthOfDuplicatedIds; i++) {
  duplicatedIds.push(new ObjectID());
}

var ArrToTest = [];
// change this value to increate the size of testing set
var lengthOfArrayToTest = 8000;

for (var j = 0; j < lengthOfArrayToTest; j++) {
  ArrToTest.push(new ObjectID());
}

ArrToTest = _.shuffle(duplicatedIds.concat(ArrToTest).concat(duplicatedIds));

function runTest(func) {
  var start = new Date();
  func.call();
  var end = new Date();
  console.log('Using %s: %d milliseconds', func.name, (end.valueOf() - start.valueOf()));
}

function indexOf() {
  return _.uniq(ArrToTest);
}

function hash() {
  return Object.keys(
    ArrToTest.reduce(function(r, value) {
      r[value.toString()] = 1;
      return r;
    }, {})
  );
}

runTest(indexOf);
runTest(hash);