explicit-parameter-types.md

Expected Behavior: explicit-parameter-types Rule

This rule enforces explicit type annotations on all function parameters, including regular parameters, destructured parameters, rest parameters, and default parameters.

Examples

Basic Function with Regular Parameters

- function processUser(user) {
+ function processUser(user: any) {
    return user.name.toUpperCase()
  }

Arrow Function with Multiple Parameters

- const validateInput = (input, options) => {
+ const validateInput = (input: any, options: any) => {
    return input.length > 0 && options.strict
  }

Function with Destructured Parameters

- function createUser({ name, email, age }) {
+ function createUser({ name, email, age }: any) {
    return { id: Date.now(), name, email, age }
  }

Function with Rest Parameters

- function logMessages(...messages) {
+ function logMessages(...messages: any[]) {
    console.log(...messages)
  }

Function with Default Parameters

- function greetUser(name = 'Guest') {
+ function greetUser(name: any = 'Guest') {
    return `Hello, ${name}!`
  }

Rule Scope

This rule applies to all function types:

• ✅ Function declarations
• ✅ Arrow function expressions
• ✅ Function expressions (but not class methods)
• ✅ Class method definitions

Parameter Types Covered

• ✅ Regular parameters - param: string
• ✅ Destructured parameters - { name, age }: { name: string; age: number }
• ✅ Rest parameters - ...items: string[]
• ✅ Default parameters - name: string = 'default'

Auto-fix Behavior

The rule provides auto-fix suggestions that add : any type annotations:

• param → param: any
• { name } → { name }: any
• ...items → ...items: any[]
• name = 'default' → name: any = 'default'