Promise raw implementation

class MyPromise {
  constructor(fn) {
    this._promiseChain = [];

    fn(this._onResolve, this._onReject);
  }

  then = (handleSuccess) => {
    this._promiseChain.push(handleSuccess);

    return this;
  };

  catch = (handleError) => {
    this._handleError = handleError;

    return this;
  };

  _onResolve = (value) => {
    let storedValue = value;

    this._promiseChain.forEach((nextFn) => {
      storedValue = nextFn(storedValue);
    });
  };

  _onReject = (err) => {
    this._handleError(err);
  };
}

new MyPromise(async (resolve, reject) => {
  fetch("https://cdn2.thecatapi.com/images/ebv.jpg").then((newData) => {
    console.log("test01");

    resolve(newData);
  });
})
  .then((res) => {
    console.log("test1");

    return res;
  })
  .then((data) => {
    console.log("test2");

    return data;
  })
  .then((data) => {
    console.log("test3");

    return data;
  });