The "=" operator always returns the value on the right side, and it always processes the right side before the left side.

Therefore:

1 - this.mutation = this.get // returns this.get

2 - this.query = <return value of this.mutation = this.get, which is this.get>

3 - this.patch = <return value of this.query = this.mutation = this.get, which is this.get>

n - and so on...

Essentially, it's setting 6 different properties all to the same value.

---

EDIT: Here's the same concept, but in a different context...

function fibonacci(num, memo = {}) {

    if (num <= 1) return 1;

    if (memo[num]) return memo[num];

    return memo[num] = fibonacci(num - 1, memo) + fibonacci(num - 2, memo);

}

On the return line, the right-to-left property of "=" forces the extreme right to be processed first. It returns the recursive call.

Then, the return value of this recursive call gets saved to "memo[num]".

Finally, the return value of "memo[num] = fibonacci(...) + fibonacci(...)", which is still the same return value from the recursive call, gets saved to the function return.

Thanks for taking time to put an example. I am familiar with the assignment rule, but this is a refresher. My question was more on why it was one function being used for all others.

Ah, well, could be useful for someone else who looks at it.

The reason you'd do this is because you are probably planning to return the same response for all the HTTP verbs.

Like if you wanted to return a empty hash {} for:

  GET /
  DELETE /
  PUT /
  PATCH /
  POST /

I guess just being lazy.

Not sure if it answers your whole question but it means that the value of this.get gets assigned to all the other variables.

Makes sense, but why do we have to do it this way, assigning just get func to all other verbs (functions), cos this is an example?

It turns six lines into one line.

It looks impressive in software interviews, but I don't really see the use in it for production code. Not every JS dev immediately knows what's going on with this syntax.