添加3个数组求并集,交集和差集的方法

src/common/Extend.ts

@@ -563,6 +563,23 @@ interface Array<T> {
      * @param n n > 0 右移, n<0 左移
      */
     moveElement?<T>(n: number): T[];
+
+    /**
+     * 两个数组并集
+     * @param arr
+     */
+    union?<T>(arr: T[]): T[];
+
+    /**
+     * 两个数组交集
+     * @param arr
+     */
+    intersect?<T>(arr: T[]): T[];
+    /**
+     * 相对于arr的差集
+     * @param arr
+     */
+    difference?<T>(arr: T[]): T[];
 }
 
 Object.defineProperties(Array.prototype, {
@@ -815,6 +832,32 @@ Object.defineProperties(Array.prototype, {
             return this.slice(-n).concat(this.slice(0, -n));
         },
         writable: true
+    },
+
+    union: {
+        value: function<T> (this: T[], b: any[]): T[] {
+            let a = this.concat(b);
+            return [...new Set(a)];
+        },
+        writable: true
+    },
+
+    intersect: {
+        value: function<T> (this: T[], b: any[]): T[] {
+            let set0 = new Set(b);
+            let set1 = new Set(this.filter (x => set0.has(x)));
+            return [...set1];
+        },
+        writable: true
+    },
+
+    difference: {
+        value: function<T> (this: T[], b: any[]): T[] {
+            let set0 = new Set(b);
+            let set1 = new Set(this.filter(x => !set0.has(x)));
+            return [...set1];
+        },
+        writable: true
     }
 
 });