let obj:object; // 定义了一个只能保存对象的变量
// obj = 1;
// obj = "123";
// obj = true;
obj = {name:'lnj', age:33};
console.log(obj);

// 需求: 要求定义一个函数输出一个人完整的姓名, 这个人的姓必须是字符串, 这个人的名也必须是一个字符interface FullName{firstName:stringlastName:string
}let obj = {firstName:'Jonathan',lastName:'Lee'// lastName:18 会报错
};//{firstName, lastName}使用了解构赋值
function say({firstName, lastName}:FullName):void {console.log(`我的姓名是:${firstName}_${lastName}`);
}
say(obj);

// 需求: 如果传递了middleName就输出完整名称, 如果没有传递middleName, 那么就输出firstName和lastName
interface FullName{firstName:stringlastName:stringmiddleName?:string[propName:string]:any
}function say({firstName, lastName, middleName}:FullName):void {// console.log(`我的姓名是:${firstName}_${lastName}`);if(middleName){console.log(`我的姓名是:${firstName}_${middleName}_${lastName}`);}else{console.log(`我的姓名是:${firstName}_${lastName}`);}
}say({firstName:'Jonathan', lastName:'Lee', middleName:"666"});
say({firstName:'Jonathan', lastName:'Lee'});

interface FullName {[propName:string]:string
}
let obj:FullName = {// 注意点: 只要key和value满足索引签名的限定即可, 无论有多少个都无所谓firstName:'Jonathan',lastName:'Lee',// middleName:false // 报错// 无论key是什么类型最终都会自动转换成字符串类型, 所以没有报错// false: '666'
}interface stringArray {[propName:number]:string
}let arr:stringArray = {0:'a',1:'b',2:'c'
};// let arr:stringArray = ['a', 'b', 'c'];
console.log(arr[0]);
console.log(arr[1]);
console.log(arr[2]);

interface LengthInterface {length:number}interface WidthInterface {width:number}interface HeightInterface {height:number}interface RectInterface extends LengthInterface,WidthInterface,HeightInterface {// length:number// width:number// height:numbercolor:string}let rect:RectInterface = {length:10,width:20,height:30,color:'red'}

interface SumInterface {(a:number, b:number):number
}// 建议使用这种写法
let sum:SumInterface= function(x,y) {return x + y;
}let res = sum(10, 20);console.log(res);