var stuff: { [key: string]: string; } = {};
stuff['a'] = ''; // ok
stuff['a'] = 4;  // error

// ... or, if you're using this a lot and don't want to type so much ...
interface StringMap { [key: string]: string; }
var stuff2: StringMap = { };
// same as above

var stuff: { [key: string]: string; } = {};
stuff['a'] = ''; // ok
stuff['a'] = 4;  // error

// ... or, if you're using this a lot and don't want to type so much ...
interface StringMap { [key: string]: string; }
var stuff2: StringMap = { };
// same as above

interface AgeMap {
    [name: string]: number
}

const friendsAges: AgeMap = {
    "Sandy": 34,
    "Joe": 28,
    "Sarah": 30,
    "Michelle": "fifty", // ERROR! Type 'string' is not assignable to type 'number'.
};

在这里，接口AgeMap强制键为字符串，值为数字。关键字名称可以是任何标识符，应该用于建议接口/类型的语法。

你可以使用类似的语法来强制一个对象对union类型中的每个条目都有一个键:

type DayOfTheWeek = "sunday" | "monday" | "tuesday" | "wednesday" | "thursday" | "friday" | "saturday";

type ChoresMap = { [day in DayOfTheWeek]: string };

const chores: ChoresMap = { // ERROR! Property 'saturday' is missing in type '...'
    "sunday": "do the dishes",
    "monday": "walk the dog",
    "tuesday": "water the plants",
    "wednesday": "take out the trash",
    "thursday": "clean your room",
    "friday": "mow the lawn",
};

当然，您也可以将其设置为泛型类型!

type DayOfTheWeek = "sunday" | "monday" | "tuesday" | "wednesday" | "thursday" | "friday" | "saturday";

type DayOfTheWeekMap<T> = { [day in DayOfTheWeek]: T };

const chores: DayOfTheWeekMap<string> = {
    "sunday": "do the dishes",
    "monday": "walk the dog",
    "tuesday": "water the plants",
    "wednesday": "take out the trash",
    "thursday": "clean your room",
    "friday": "mow the lawn",
    "saturday": "relax",
};

const workDays: DayOfTheWeekMap<boolean> = {
    "sunday": false,
    "monday": true,
    "tuesday": true,
    "wednesday": true,
    "thursday": true,
    "friday": true,
    "saturday": false,
};

10.10.2018更新: 看看下面@dracstaxi的答案——现在有一个内置的类型Record，它可以帮你完成大部分工作。

1.2.2020更新: 我已经完全从我的回答中删除了预先制作的映射接口。@dracstaxi的回答让他们完全无关紧要。如果您仍然想使用它们，请检查编辑历史记录。

type KeyOf<T> = keyof T;

class SomeClass<T, R> {
  onlyTFieldsAllowed = new Map<KeyOf<T>, R>();
}

class A {
  myField = 'myField';
}

const some = new SomeClass<A, any>();

some.onlyTFieldsAllowed.set('myField', 'WORKS');
some.onlyTFieldsAllowed.set('noneField', 'Not Allowed!');

@Ryan Cavanaugh的回答完全没问题，而且仍然有效。值得补充的是，在16年秋季，当我们可以宣称ES6被大多数平台支持时，当你需要将一些数据与一些键关联时，几乎总是更好地坚持使用Map。

当我们写let a: {[s:字符串]:字符串;}我们需要记住typescript编译后没有类型数据这样的东西，它只用于编译。和{[s:字符串]:字符串;}将编译为{}。

也就是说，即使你写的是:

class TrickyKey  {}

let dict: {[key:TrickyKey]: string} = {}

这只是不会编译(即使对于目标es6，你也会得到错误TS1023:索引签名参数类型必须是'string'或'number'。

实际上，字符串或数字作为潜在的键是有限的，所以这里没有太多强制类型检查的意义，特别是要记住，当js试图通过数字访问key时，它会将其转换为字符串。

因此，假设最佳实践是使用Map，即使键是字符串，这是相当安全的，所以我坚持使用:

let staff: Map<string, string> = new Map();

实际上有一个内置的实用程序记录:

    const record: Record<string, string> = {};
    record['a'] = 'b';
    record[1] = 'c'; // leads to typescript error
    record['d'] = 1; // leads to typescript error