Nodejs Array Unique unique2(getKey = val => val)

Method Source Code

Array.prototype.unique2 = function (getKey = val => val) {
  const n = {};/*from w  ww  .j av a2s .c o m*/
  const r = [];
  for (let i = 0; i < this.length; i += 1) {
    const key = getKey(this[i]);
    if (!n[key]) {
      n[key] = true;
      r.push(this[i]);
    }
  }
  return r;
};

Related

1. unique1()

   Array.prototype.unique1 = function () {
     var a = [],
       o = {},
       n = this.length;
       for (var i=0; i<n; ++i) {
         o[this[i]] = this[i];
       for (var i in o) {
         a.push(o[i]);
   ...
   

2. unique2()

   Array.prototype.unique2 = function(){
    this.sort(); 
    var res = [this[0]];
    for(var i = 1; i < this.length; i++){
     if(this[i] !== res[res.length - 1]){
      res.push(this[i]);
    return res;
   ...
   

3. unique2()

   Array.prototype.unique2=function () {
       var n={};
       var tmp=[];
       for(var i=0;i<this.length;i++){
           if(!n[this[i]]){
               n[this[i]]=true;
               tmp.push(this[i]);
       return tmp;
   

4. unique2()

   Array.prototype.unique2 = function () {
     var a = [],
       n = this.length;
       for (var i=0; i<n; ++i) {
         for (var j=i+1; j<n; ++j) {
           if(this[i]===this[j]) j = ++i;
         a.push(this[i]);
     return a;
   };
   

5. unique2()

   Array.prototype.unique2 = function () {
     var result = [];
     for (var i = 0; i < this.length; i++) {
       if (result.indexOf(this[i]) == -1) {
         result.push(this[i]);
     return result;
   

6. unique3()

   Array.prototype.unique3 = function () {
     return this.filter(function (s, i, a) {
       return i===a.lastIndexOf(s);
     })
   };
   

7. unique3()

   Array.prototype.unique3 = function(){
    var res = [];
    var json = {};
    var dejson = {};
    var length = 0;
    for(var i = 0; i < this.length; i++){
     if(!json[this[i].name]){
      dejson[this[i]] = this[i];
      console.log(dejson[this[i]]);
   ...
   

8. unique3()

   Array.prototype.unique3 = function(){
     var res = [1,2,3,4,1,2,3,4];
     var json = {};
     for(var i = 0; i < this.length; i++){
         if(!json[this[i]]) {
           res.push(this[i]);
           json[this[i]] = true;
     return res;
   console.log(unique3());
   

9. unique5()

   Array.prototype.unique5 = function() {
       var res = [], hash = {};
       for(var i=0, elem; (elem = this[i]) != null; i++)  {
           if (!hash[elem])
               res.push(elem);
               hash[elem] = true;
       return res;