typeScript基础

let isDone: boolean = false;
let decLiteral: number = 6
let sentence: string = `Hello, my name is ${myName}`
let myFavoriteNumber: any = 'seven';  // 如果是 any 类型，则允许被赋值为任意类型
let myFavoriteNumber: string | number; // 联合类型（Union Types）表示取值可以为多种类型中的一种
let fibonacci: number[] = [1, 1, 2, 3, 5]; // 最简单的方法是使用「类型 + 方括号」来表示数组
let fibonacci: (number | string)[] = [1, '1', 2, 3, 5]; // 添加多个类型
let fibonacci: Array<number> = [1, 1, 2, 3, 5]; // 数组泛型
let list: any[] = ['xcatliu', 25, { website: 'http://xcatliu.com' }]; // 一个比较常见的做法是，用 any 表示数组中允许出现任意类型

let createdByNewBoolean: boolean = new Boolean(1);
// Type 'Boolean' is not assignable to type 'boolean'.
//   'boolean' is a primitive, but 'Boolean' is a wrapper object. Prefer using 'boolean' when possible.

function alertName(): void {
    alert('My name is Tom');
}

let unusable: void = undefined;

// 在定义的变量比接口少了一些属性或多一些属性是不允许的，赋值的时候，变量的形状必须和接口的形状保持一致。
interface Person {
    name: string;
    age: number;
}

let tom: Person = {
    name: 'Tom'
};
// index.ts(6,5): error TS2322: Type '{ name: string; }' is not assignable to type 'Person'.
//   Property 'age' is missing in type '{ name: string; }'.

interface Person {
    name: string;
    age?: number;
}

let tom: Person = {
    name: 'Tom'
};

interface Person {
    name: string;
    age?: number;
    [propName: string]: any;
}

let tom: Person = {
    name: 'Tom',
    gender: 'male'
};

// 需要注意的是，一旦定义了任意属性，那么确定属性和可选属性的类型都必须是它的类型的子集：
// 任意属性的值允许是 string，但是可选属性 age 的值却是 number，number 不是 string 的子属性，所以报错了
interface Person {
    name: string;
    age?: number;
    [propName: string]: string;
}

let tom: Person = {
    name: 'Tom',
    age: 25,
    gender: 'male'
};
// index.ts(3,5): error TS2411: Property 'age' of type 'number' is not assignable to string index type 'string'.
// index.ts(7,5): error TS2322: Type '{ [x: string]: string | number; name: string; age: number; gender: string; }' is not assignable to type 'Person'.
//   Index signatures are incompatible.
//     Type 'string | number' is not assignable to type 'string'.
//       Type 'number' is not assignable to type 'string'.

interface Person {
    readonly id: number;
    name: string;
    age?: number;
    [propName: string]: any;
}

let tom: Person = {
    id: 89757,
    name: 'Tom',
    gender: 'male'
};

tom.id = 9527;
// index.ts(14,5): error TS2540: Cannot assign to 'id' because it is a constant or a read-only property.

// NumberArray 表示：只要索引的类型是数字时，那么值的类型必须是数字。
interface NumberArray {
    [index: number]: number;
}
let fibonacci: NumberArray = [1, 1, 2, 3, 5];

function sum() {
    let args: IArguments = arguments;
}

interface IArguments {
    [index: number]: any;
    length: number;
    callee: Function;
}

function sum(x: number, y: number): number {
    return x + y;
}

let mySum = function (x: number, y: number): number {
    return x + y;
};
let tomcat = buildName('Tom', 'Cat');
let tom = buildName('Tom');

function buildName(firstName: string, lastName?: string) {
    if (lastName) {
        return firstName + ' ' + lastName;
    } else {
        return firstName;
    }
}

function buildName(firstName: string, lastName: string = 'Cat') {
    return firstName + ' ' + lastName;
}
let tomcat = buildName('Tom', 'Cat');
let tom = buildName('Tom');

interface SearchFunc {
    (source: string, subString: string): boolean;
}

let mySearch: SearchFunc;
mySearch = function(source: string, subString: string) {
    return source.search(subString) !== -1;
}

function getLength(something: string | number): number {
    if (something.length) {
        return something.length;
    } else {
        return something.toString().length;
    }
}
// index.ts(2,19): error TS2339: Property 'length' does not exist on type 'string | number'.
//   Property 'length' does not exist on type 'number'.
// index.ts(3,26): error TS2339: Property 'length' does not exist on type 'string | number'.
//   Property 'length' does not exist on type 'number'.

function getLength(something: string | number): number {
    if ((<string>something).length) {
        return (<string>something).length;
    } else {
        return something.toString().length;
    }
}

let b: Boolean = new Boolean(1);
let e: Error = new Error('Error occurred');
let d: Date = new Date();
let r: RegExp = /[a-z]/;
let body: HTMLElement = document.body;
let allDiv: NodeList = document.querySelectorAll('div');
document.addEventListener('click', function(e: MouseEvent) {
  // Do something
});