Ts学习总结（11/20）——函数

函数定义

function hello(name: string): void {
  console.log("hello", name);
}
hello("echo");

函数表达式

type MaxFunc = (x: number, y: number) => number;

let maxNumber: MaxFunc = function (a, b) {
  return a>b?a:b;
};

可选参数

function print(name: string, age?: number): void {
  console.log(name, age);
}
print("echo");

默认参数

function ajax(url: string, method: string = "GET") {
  console.log(url, method);
}
ajax("/users");

剩余参数

function sum(...numbers: number[]) {
  return numbers.reduce((val, item) => (val += item), 0);
}
console.log(sum(1, 2, 3));

函数重载

let obj: any = {};
function attr(val: string): void;
function attr(val: number): void;
function attr(val: any): void {
  if (typeof val === "string") {
    obj.name = val;
  } else {
    obj.age = val;
  }
}
attr("echo");
attr(9);
attr(true);
console.log(obj);