[Solved]-'string' can't be used to index type '{}'-Reactjs

try adding type any[]

items:any[]

First of all, defining the type of items as an array of objects is a bad idea, as it defeats the purpose of Typescript. Instead define what type of objects the array will contain. I would do it this way:

type Item = {
  id: number,
  name: string,
  email: string,
}

export type TableGridViewProps = {
  items: Item[],
  tableColumns: TableColumn[]
};

After that if you're absolutely sure that the key would exist in item, you can do the following to tell Typescript that you are accessing a valid index.

<td
  key={column.key}
  className="lorem ipsum"
>
  {item[column.key as keyof typeof Item]}
</td>

Use Generics

// bad
const _getKeyValue = (key: string) => (obj: object) => obj[key];

// better
const _getKeyValue_ = (key: string) => (obj: Record<string, any>) => obj[key];

// best
const getKeyValue = <T extends object, U extends keyof T>(key: U) => (obj: T) =>
      obj[key];

Bad - the reason for the error is the object type is just an empty object by default. Therefore it isn't possible to use a string type to index {}.

Better - the reason the error disappears is because now we are telling the compiler the obj argument will be a collection of string/value (string/any) pairs. However, we are using the any type, so we can do better.

Best - T extends empty object. U extends the keys of T. Therefore U will always exist on T, therefore it can be used as a look up value.

Here is a full example:

I have switched the order of the generics (U extends keyof T now comes before T extends object) to highlight that order of generics is not important and you should select an order that makes the most sense for your function.

const getKeyValue = <U extends keyof T, T extends object>(key: U) => (obj: T) =>
  obj[key];

interface User {
  name: string;
  age: number;
}

const user: User = {
  name: "John Smith",
  age: 20
};

const getUserName = getKeyValue<keyof User, User>("name")(user);

// => 'John Smith'

If it's a pedantic javascript object that doesn't make sense to create type definitions per field for, and doesn't make sense as a class definition, you can type the object with any and typescript will let you index however you want.

ex.

//obviously no one with two brain cells is going to type each field individually
let complicatedObject: any = {
    attr1: 0,
    attr2: 0,
    ...
    attr999: 0
}

Object.keys(complicatedObject).forEach(key => {
    complicatedObject[key] += 1;
}