<h2>ES6 Proxy:</h2>
<pre><code>

interface createCounterFnc {
  (): { readonly count: number };
}

const createCounter: createCounterFnc = () =&gt; {
  let count = 0;
  return new Proxy(
    { count },
    {
      // getter proxy.count count++
      get(target, p, receiver) {
        if (p === "count") {
          count++;
          console.log("count++", count);
          return count;
        }
        return Reflect.get(target, p, receiver);
      },
      // setter proxy.count
      set(target, p, value, receiver) {
        if (p === "count") {
          //   throw new Error("count is readonly");
          return false;
        }
        return Reflect.set(target, p, value, receiver);
      },
    }
  );
};

const counter = createCounter();
counter.count; // 1
counter.count; // 2
counter.count; // 3
// 无法为“count”赋值，因为它是只读属性。ts(2540)
counter.count = 10; // Error "count is readonly"

</code></pre>
<hr />
<h2>ES5  Object.defineProperties</h2>
<pre><code>interface CreateCounterFnc {
  (): { readonly count: number };
}

const createCounter: CreateCounterFnc = () =&gt; {
  let count = -1;

  const obj = Object.defineProperties(Object.create(null), {
    count: {
      get: function () {
        count++;
        console.log("count++", count);
        return count;
      },
      configurable: false, // 防止重新配置属性
      enumerable: true, // 允许在for...in循环中枚举
      writable: false, // 设置为只读
    },
  });

  return obj;
};

const counter = createCounter();
counter.count;
counter.count;
counter.count;
counter.count = 20; // 无法为“count”赋值，因为它是只读属性。ts(2540)
</code></pre>
<hr />
<h2>TypeScript Class</h2>
<pre><code>class CounterManagement {
  private _count = -1;

  public get count(): number {
    this._count++;
    console.log("count", this._count);
    return this._count;
  }
}

const createCounter = () =&gt; new CounterManagement();

const counter = createCounter();
counter.count;
counter.count;
counter.count;
(counter as any).count = 300; // 无法为“count”赋值，因为它是只读属性。


</code></pre>
<p>compiled code:</p>
<pre><code>var CounterManagement = /** @class */ (function () {
    function CounterManagement() {
        this._count = -1;
    }
    Object.defineProperty(CounterManagement.prototype, "count", {
        get: function () {
            this._count++;
            console.log("count", this._count);
            return this._count;
        },
        enumerable: false,
        configurable: true
    });
    return CounterManagement;
}());
var createCounter = function () { return new CounterManagement(); };
var counter = createCounter();
counter.count;
counter.count;
counter.count;
counter.count = 300; // 无法为“count”赋值，因为它是只读属性。


</code></pre>

Using Different ways to implement createCounter function

Create an object with property count, which increments every time count is accessed, initial value is 0. const counter = createCounter() counter.count…