Typescript typing recipes

Typescript-typing-recipes.md

Useful Type Rules That Saves You Looking It Up

Reduce

let count = -1;
const array = ReadonlyArray<T>;

array.reduce<{[k in string]: T}>((acc: {[k in string]: T}, entry) => ({
  //              ^-->acc-type               ^--->acc-type
  count = count + 1;
  return {
    ...acc,
    [count]: array[count]
  }
}, {})

The count stuff is all bad and I can be ignored, whats important here is the typing for acc. I'm pretty sure you don't need it typed in both places.