snippets.ts

// Argument type based on value of another argument

type OrderType = 'Simple' | 'Extended'

interface OrderOptionsSet = {
  Simple: {
    name: string
    age: number
  },
  Extended: {
    firstName: string
    lastName: string
    something: any
  }
}

async createTask<K extends OrderType>(type: K, options: OrderOptionsSet[K]): Promise<any> {
  // options type now will be OrderOptionsSet.Simple or OrderOptionsSet.Extended here bdepending on type value
}
  
// Return type based on return type of function, passed as argument

export async function waitUntil<T>(fn: () => T, timeoutSec: number = 30): Promise<T> {
  // ...
}