add: menambahkan file materi decorator

Author: Mednoob

TypeScriptBasic/0x_Decorators/Decorators.test.ts

@@ -0,0 +1,14 @@
+import { StringUtility } from "./Decorators";
+
+test("[TypeScriptBasic/0x_Decorators] Pengecekan Class Decorator", () => {
+    expect(new StringUtility(["Test"]).data[0]).toBe("Teks pengganti argumen pertama");
+})
+
+test("[TypeScriptBasic/0x_Decorators] Pengecekan Property Decorator", () => {
+    // @ts-expect-error
+    expect(new StringUtility("abc")).toThrowError();
+})
+
+test("[TypeScriptBasic/0x_Decorators] Pengecekan Method Decorator", () => {
+    expect(StringUtility.prototype.sambungData = () => { return "" }).toThrowError();
+})

TypeScriptBasic/0x_Decorators/Decorators.ts

@@ -0,0 +1,44 @@
+// Penjelasan akan ditulis nanti.
+
+function gantiArgumenConstructor(constructor: typeof StringUtility): any {
+    return class extends constructor {
+        constructor(args: string[]) {
+            super(["Teks pengganti argumen pertama", ...args]);
+        }
+    }
+}
+
+function buatMethodTidakDapatDiubah(target: any, key: string, descriptor: PropertyDescriptor) {
+    descriptor.writable = false;
+}
+
+function harusBerupaArray(target: any, key: string) {
+    if (!Array.isArray(target[key])) {
+        throw new Error(`${key} harus berupa array`);
+    }
+}
+
+@gantiArgumenConstructor
+class StringUtility {
+    @harusBerupaArray
+    public data: string[];
+
+    constructor(data: string[]) {
+        this.data = data;
+    }
+
+    @buatMethodTidakDapatDiubah
+    sambungData(separator: string): string {
+        return this.data.join(separator);
+    }
+
+    // Bisa digunakan juga pada accessor property
+    @buatMethodTidakDapatDiubah
+    get dataKapital(): string[] {
+        return this.data.map(data => data.toUpperCase());
+    }
+}
+
+export {
+    StringUtility
+}