What kind of array is passed to the Express post request?

Question

What does this array do in the router's post request?

router.post(
  "/register",
  [
    check("email", "Некорректный email").isEmail(),
    check("password", "Минимальная длина пароля 6 символов").isLength({ min: 6 })
  ],
  () => { ... }

(Just a sample code) What is this array for? I didn't find this parameter in the docs, it only talked about path and callback parameters.

Comments

https://expressjs.com/en/4x/api.html#app.post.method

Callback functions; can be:

A middleware function.
A series of middleware functions (separated by commas).
An arrayof middleware functions.
A combination of all of the above.

Answer 1

After the first argument comes a sequence of midvars (any number of them). You have an array of midvars first, and then a normal midvar function.

It's described in the doc:

Answer 2

Well, everything has already been answered, and so it's express-validator
https://express-validator.github.io/docs/validatio...