元素隐式具有“any”类型，因为“any”类型的表达式不能用于索引 TypeScript 中的“{}”类型

Question

I have code like this:

const arr = [3, 3, 2, 1, 4, 5];

const count = {};

arr.forEach((element:any) => {
  count[element] = (count[element] || 0) + 1;
});
console.log(count);

The expected output is like this: { '1': 1, '2': 1, '3': 2, '4': 1, '5': 1 }

This works fine in JavaScript, but in TypeScript I am getting an error like this:

Element implicitly has an 'any' type because expression of type 'any' can't be used to index type '{}'.

I have tried giving type of element to number also but it did not work.

Answer 1

Typing your count should fix it, I'd also remove element:any and just replace it with element as its type should be inferenced from when you create the array

const count = {} as { [key: number]: number };