this.methodName is undefined in browser, Can’t use the this.MethodName between internal methods in Typescript Class

I have my typescript files bundled into one file. Called them like this:

export class MyComponent extends CommonComponent {

  private fooMethod() {
    // normal typescript code here.
  }

  public barMethod() {
    this.fooMethod();
  }
}

and all these are translated to javascript like this: MyComponent.prototype.fooMethod = () => { // the code here }. The problem is that this.fooMethod in the barMethod is undefined in the javascript. How can resolve that?

I was cheking all the net for same question, didn’t find any. I would appreciate it if you help me or address me any resource on net regarding this topic. Thanks.