@typescript-eslint/max-params

A call like createUser("Ada", "ada@example.com", true, false) says nothing about what each argument means, and you can swap two arguments of the same type without getting an error. Past three parameters, one object with named properties is easier to read and to extend.

It's the TypeScript version of max-params. It checks function types too, and it doesn't count a this: void parameter.

Configure#

Off by default. To turn it on:

bunfig.toml

[lint.rules]
"@typescript-eslint/max-params" = "error" # or "warn"

Every option, set to its default. The ones that are commented out are unset by default.

bunfig.toml

[lint.rules]
"@typescript-eslint/max-params" = ["error", {
  max = 3,
  # maximum = <number>,
  countVoidThis = false,
}]

Examples#

Reported:

function createUser(name: string, email: string, isAdmin: boolean, isActive: boolean) {
  return { name, email, isAdmin, isActive };
}

Not reported:

interface NewUser {
  name: string;
  email: string;
  isAdmin: boolean;
  isActive: boolean;
}

function createUser(user: NewUser) {
  return { ...user };
}

function move(this: void, x: number, y: number, z: number) {}

Options#

Option	Default	What it does
`max`	`3`	The number of parameters a function can have.
`maximum`		An older name for `max`.
`countVoidThis`	`false`	Count a `this: void` parameter like any other.

type Add = (left: number, right: number) => number;

function move(this: void, x: number, y: number, z: number) {}

A this parameter of any other type is always counted:

function move(this: Window, x: number, y: number, z: number) {}