Set class in ES6

Author: loiane

chapter06/01-Set2.js

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+let Set2 = (function () {
+
+    const items = new WeakMap();
+
+    class Set2 {
+
+        constructor () {
+            items.set(this, {});
+        }
+
+        add(value){
+            if (!this.has(value)){
+                let items_ = items.get(this);
+                items_[value] = value;
+                return true;
+            }
+            return false;
+        }
+
+        delete(value){
+            if (this.has(value)){
+                let items_ = items.get(this);
+                delete items_[value];
+                return true;
+            }
+            return false;
+        }
+
+        has(value){
+            let items_ = items.get(this);
+            return items_.hasOwnProperty(value);
+        }
+
+        clear(){
+            items.set(this, {});
+        }
+
+        size(){
+            let items_ = items.get(this);
+            return Object.keys(items_).length;
+        }
+
+
+        values(){
+            let values = [];
+            let items_ = items.get(this);
+            for (let i=0, keys=Object.keys(items_); i<keys.length; i++) {
+                values.push(items_[keys[i]]);
+            }
+            return values;
+        }
+
+        getItems(){
+            return items.get(this);
+        }
+
+        union(otherSet){
+            let unionSet = new Set();
+
+            let values = this.values();
+            for (let i=0; i<values.length; i++){
+                unionSet.add(values[i]);
+            }
+
+            values = otherSet.values();
+            for (let i=0; i<values.length; i++){
+                unionSet.add(values[i]);
+            }
+
+            return unionSet;
+        }
+
+        intersection(otherSet){
+            let intersectionSet = new Set();
+
+            let values = this.values();
+            for (let i=0; i<values.length; i++){
+                if (otherSet.has(values[i])){
+                    intersectionSet.add(values[i]);
+                }
+            }
+
+            return intersectionSet;
+        }
+
+        difference(otherSet){
+            let differenceSet = new Set();
+
+            let values = this.values();
+            for (let i=0; i<values.length; i++){
+                if (!otherSet.has(values[i])){
+                    differenceSet.add(values[i]);
+                }
+            }
+
+            return differenceSet;
+        };
+
+        subset(otherSet){
+
+            if (this.size() > otherSet.size()){
+                return false;
+            } else {
+                let values = this.values();
+                for (let i=0; i<values.length; i++){
+                    if (!otherSet.has(values[i])){
+                        return false;
+                    }
+                }
+                return true;
+            }
+        };
+    }
+    return Set2;
+})();