// 字符串:
// 使用单引号''和反引号``, 避免使用双引号""
// 反引号用${}插值
let a: string = 'foobar';
let b: string = `foo${a}bar`;
console.log(b);

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// 数组解构; 
let arr: Array<number> = [1, 2, 3, 4];
let [first, second] = arr;
console.log(1, first, second)
////////////////////////////////////////////////////
// 对象解构: 
interface User {firstName: string,lastName: string
}function getUserName(user: User): User {let {firstName, lastName} = user;// 当函数需要返回多个值的时候, 尽量使用对象形式的返回, 便于以后修改返回值的顺序以及添加新的返回内容return {firstName, lastName};
}console.log(2, getUserName({firstName: 'james', lastName: 'hellen'}));

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// 单行对象声明最后一项不加逗号, 
// 多行对象声明最后一行加逗号
let a: any = {k1: 1,k2: 2,k3: 3,
}let b: any = {k1: 1, k2: 2, k3: 3};
////////////////////////////////////////////////////
function getKey(): string {console.log('get key out');return 'key' + 9;
}let id: number = 1;
// 对象属性名可以动态生成
// 对象属性和接受变量的名称一致时可以简写
let obj: any = {id,name: 'Shanghai',[getKey()]: true
};
console.log(3, obj);let obj1: any = {id,value: id,getKey(key: string) {return key;},[getKey()]() {console.log('get key in');}
};
console.log(4, obj1);

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// 扩展运算符...
// 数组拷贝
let arr1: number[] = [1, 2, 3, 4];
let arrCopy: number[] = [...arr1];
console.log(5, arrCopy == arr1);

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// 箭头函数
let arr2: number[] = [1, 2, 3, 4];
arr2.sort((a, b) => Math.random() - 0.5);
console.log(6, arr2);