Nodejs Array Subset isSubsetOf(array)

Method Source Code

/*// w ww  .  j ava2  s  .  co  m
 * Make an array method that can return whether or not a context array is a
 * subset of an input array.  To simplify the problem, you can assume that both
 * arrays will contain only strings.
 *
 *
 * var a = ['commit','push']
 * a.isSubsetOf(['commit','rebase','push','blame']) // true
 *
 * NOTE: You should disregard duplicates in the set.
 *
 * var b = ['merge','reset','reset']
 *
 * b.isSubsetOf(['reset','merge','add','commit']) // true
 *
 * See http://en.wikipedia.org/wiki/Subset for more on the definition of a
 * subset.
 */

/*
 * Extra credit: Make the method work for arrays that contain any value,
 * including non-strings.
 */

Array.prototype.isSubsetOf = function(array) {
  var subArray = this;
  var map = {};

  for(var i=0;i<subArray.length;i++){
    if(!map[subArray[i]]){
      if(array.indexOf(subArray[i]) === -1){
        return false;
      }
    }

    // store in hashmap to skip over duplicates
    map[subArray[i]] = true;
  }

  return true;
};

Related

1. isSubsetOf(array)

   Array.prototype.isSubsetOf = function(array) {
     for(var i = 0; i < this.length; i++){
       if(array.indexOf(this[i])===-1){
         return false
     return true;
   };
   

2. isSubsetOf(array)

   Array.prototype.isSubsetOf = function(array) {
     var isSubset = true;
     if(this.forEach(function(element){
       if(!array.includes(element)){
         isSubset = false;
     }));
     return isSubset;
   };
   ...
   

3. isSubsetOf(array)

   Array.prototype.isSubsetOf = function(array) {
     var result = true;
     for (var i = 0; i < this.length; i ++) {
       if(array.indexOf(this[i]) === -1) {
         result = false;
     return result;
   };
   ...
   

4. isSubsetOf(array)

   Array.prototype.isSubsetOf = function(array) {
     var arr = this;
     var obj = {};
     for(var i=0; i<array.length; i++) {
       obj[array[i]] = true; 
     for(var i=0; i<arr.length; i++) {
       if(!(arr[i] in obj)) {
         return false;
   ...
   

5. isSubsetOf(array)

   Array.prototype.isSubsetOf = function (array) {
     var subset    = this;
     var subsetLen = subset.length;
     var supersetLen = array.length;
     var first, found;
     if ( subsetLen > supersetLen ) return false;
     if ( subsetLen === 0 && supersetLen >= 0 ) return true;
     first = subset[0];
     found = array.indexOf( first );
   ...
   

6. isSubsetOf(array)

   Array.prototype.isSubsetOf = function(array) {
     function arrayContains(array, item) {
       for (var i = 0; i < array.length; i++) {
         if (array[i] === item) {
           return true;
       return false;
     for (var i = 0; i < this.length; i++) {
       if (!arrayContains(array, this[i])) {
         return false;
     return true;
   

7. isSubsetOf(array)

   var a = ['commit', 'push'];
   var b = ['merge', 'reset', 'reset'];
   Array.prototype.isSubsetOf = function (array) {
     for (var i = 0; i < this.length; i++) {
       if (array.indexOf(this[i]) === -1) {
         return false;
     return true;
   ...
   

8. isSubsetOf(bigArray)

   Array.prototype.isSubsetOf = function(bigArray) {
     var uniqueSub = this.unique();
     var uniqueBig = bigArray.unique();
     var status = true;
     this.forEach(function(item) {
       if(bigArray.indexOf(item) === -1) status = false;
     });
     return status;
   };
   ...
   

9. isSubsetOf(comparisonArray)

   Array.prototype.isSubsetOf = function(comparisonArray) {
     for (var i = 0; i < this.length; i++) {
       if (comparisonArray.indexOf(this[i]) === -1) {
         return false;
     return true;
   };