在typescript中通过键获取对象的值

type MyObject = {
  [key: string]: number; // 键为字符串，值为数字
};

const obj: MyObject = {
  key1: 10,
  key2: 20,
};

console.log(obj['key1']); // 输出 10
console.log(obj['key2']); // 输出 20

const obj: any = {
  key1: 'value1',
  key2: 'value2',
};

const value1 = obj['key1'] as string;
const value2 = <string>obj['key2'];

console.log(value1); // 输出 'value1'
console.log(value2); // 输出 'value2'

const obj = {
  key1: 'value1',
  key2: 'value2',
};

console.log(obj?.key1); // 输出 'value1'
console.log(obj?.key2); // 输出 'value2'
console.log(obj?.key3); // 输出 undefined