javascript decorator

Author: ChauDinh

Decorator/index.js

@@ -0,0 +1,97 @@
+// function calc(x) {
+//   // Complexity
+//   console.log(`Calc with ${x}`);
+//   return x;
+// }
+
+// function cachingDecorator(func) {
+//   const cache = new Map();
+
+//   return function(x) {
+//     if (cache.has(x)) {
+//       return cache.get(x);
+//     }
+
+//     const result = func(x);
+//     cache.set(x, result);
+
+//     return result;
+//   };
+// }
+
+// calc = cachingDecorator(calc);
+
+// console.log(calc(1));
+
+// console.log(calc(1));
+
+// console.log(calc(2));
+
+// console.log(calc(2));
+// console.log(calc(2));
+
+// const worker = {
+//   multiplier: 2,
+//   calc: function(x) {
+//     console.log(`Calc with ${x}`);
+//     return x * this.multiplier;
+//   }
+// };
+
+// function cachingDecorator(func) {
+//   const cache = new Map();
+
+//   return function(x) {
+//     if (cache.has(x)) {
+//       return cache.get(x);
+//     }
+
+//     const result = func.call(this, x);
+//     cache.set(x, result);
+
+//     return result;
+//   };
+// }
+
+// worker.calc = cachingDecorator(worker.calc);
+
+// console.log(worker.calc(10));
+// console.log(worker.calc(10));
+
+// const numbers = [4, 5, 6, 7, 8, 9, 2, 3, 0, 1];
+// const max = Math.max.apply(null, numbers);
+// const min = Math.min.apply(null, numbers);
+
+// console.log(max, min);
+
+const worker = {
+  calc(min, max) {
+    console.log(`Calc with ${min}, and ${max}`);
+    return min + max;
+  }
+};
+
+function cachingDecorator(func, hash) {
+  let cache = new Map();
+
+  return function(...args) {
+    let key = hash(args);
+    if (cache.has(key)) {
+      return cache.get(key);
+    }
+
+    let result = func.apply(this, args);
+    cache.set(key, result);
+
+    return result;
+  };
+}
+
+function hash(...args) {
+  return args.join();
+}
+
+worker.calc = cachingDecorator(worker.calc, hash);
+console.log(worker.calc(1, 2));
+
+console.log(worker.calc(1, 2));