Learning Redux

Defining the use method

Now, we need to define the use method, which takes a middleware function as an argument and adds it to the middleware chain:

1. Define the use method:

  use (fn) {

2. First, we store a reference to the preceding middleware function:

    const previousFn = this.middleware

3. Next, we overwrite this.middleware with a new middleware function:

    this.middleware = (next) =>

4. In this middleware function, we first call the previous middleware function via .call(this, next) so that the this context is retained:

      previousFn.call(this, () =>

5. In the passed function, we call the current middleware function and pass the next argument to it:

        fn.call(this, next)      )  }