Practicing with TypeScript Class readonly modifier

typescript_class_readonly_modifier.ts

class TestReadOnly {
  readonly testProp: string = "sup man";

  constructor(newValue?: string) {
    if (newValue !== undefined) {
      this.testProp = newValue;
    }
  }
}

const g = new TestReadOnly();
console.log(g.testProp);

const z = new TestReadOnly("a new value");
console.log(z.testProp);