title: What is the usage of Private and Protected Constructors in Typescript
body: <p>I noticed that in Typescript you can define constructor to be with any access modifier (private, protected, public). What will be the usage of this can someone give a valid example how to use private and protected constructors in Typescript ?</p>
  
  <p>Example this is a valid code in Typescript:</p>
  
  <pre><code>class A
  {
      private constructor()
      {
          console.log("hello");
      }
  }
  </code></pre>