[javascript] Typescript: No index signature with a parameter of type 'string' was found on type '{ "A": string; }

Here is the function example trim generic type of array object

const trimArrayObject = <T>(items: T[]) => {

  items.forEach(function (o) {

    for (let [key, value] of Object.entries(o)) {

      const keyName = <keyof typeof o>key;

      if (Array.isArray(value)) {

        trimArrayObject(value);

      } else if (typeof o[keyName] === "string") {

        o[keyName] = value.trim();

      }

    }

  });

};