泛型

函数的泛型

单个泛型

function getVal<T>(val: T): T {
  return val;
}

getVal<number>(1);
getVal<string>('1');

多个泛型

function getVal<T, P>(first: T, second: P) {
  return `${first}${second}`;
}

getVal<string, number>('1', 2);

类的泛型

class Manager<T> {
  constructor(private data: T[]) {}

  getItem(index: number): T {
    return this.data[index]
  }
}

const data = new Manager<number>([1])
const data1 = new Manager<string>(['a'])

泛型约束
泛型通过extends实现泛型约束

interface Person {
  name: string;
}

class Manager<T extends Person> {
  constructor(private data: T[]) {}

  getItem(index: number): string {
    return this.data[index].name;
  }
}

const data = new Manager([
  {
    name: 'tz',
  },
]);