function hashTable (){
    this.size = 0;
    this.dataStore = {};
}

hashTable.prototype.toString = function(){
        return this.dataStore.toString();
}

hashTable.prototype.enumerate = function(){
    for(var element in this.dataStore){
        console.log(element + " " + this.dataStore[element])
    }
    return this.dataStore;
}
hashTable.prototype.remove = function(key){
    if(this.dataStore.hasOwnProperty(key)){
        this.size -= 1;
        delete this.dataStore[key];
    }
}
hashTable.prototype.size = function(){
    return this.size;
}

hashTable.prototype.put = function (key, value){
    if(this.dataStore.hasOwnProperty(key)){
        throw new error ("hashtable cannot contain duplicates")
    }
    else {
        this.dataStore[key] = value;
        this.size += 1;
        return this.dataStore;
    }
}

hashTable.prototype.clear = function(){
    this.dataStore = {};
    this.size = 0;
    return this.dataStore;
}

hashTable.prototype.isEmpty = function(){
    return this.size > 0 ? false : true;
}

hashTable.prototype.contains = function(key){
    if(this.dataStore.hasOwnProperty(key)){
        return true;
    }
    else {
        return false;
    }
}
var ht = new hashTable();
console.log(ht.put("color", "red"))
ht.put("bike", "blue");
console.log(ht.isEmpty())

console.log(ht.remove("bike"))
console.log(ht.size)