1. interface UserArr{
    2.   // 只能约束下标和值
    3.   [index:number]:string
    4. }
    6. let arr: UserArr = ['html', 'css', 'js'];
    8. let data: string[];
    9. let d: Array<string>;
    10. interface UserObj{
    11.   [key: string]: string;
    12. }
    13. let obj: UserObj = {
    14.   name: 'lisi',
    15.   age: 23
    16. }