TS 的基础类型

1.布尔值

let done: boolean = true

2. 数字

let age: number = 19
let hexPx: number = 0xf00d

3. 字符串

let name: string = 'tom'

4. 数组

let list: number[] = [1, 2, 3]
let list: Array<number | string> = [1, 2, 3, 'a', 'b', 'c']

5.元祖

let x: [string, number];
x = ['abc', 10]

6. 枚举

enum Color {
    BLUE = 'blue',
    GREEN = 'green',
    RED = 'red'
}
let red:Color = Color.RED

7. Any

let notSure:any = 10
notSure = 'hello'
notSure = true

8. Void

const foo = (): void => {...}
let unuseable: void = undefined

9. null & undefined

let u: null = null
let n: undefined = undefined

10. Never

// 返回never的函数必须存在无法达到的终点
function infiniteLoop(): never {
    while (true) {
    }
}

11. Object

declare function create(o: object | null): void
create({ prop: 0 })

12. 类型断言

let someValue: any = "this is a string"

let strLength: number = (<string>someValue).length
# 两种写法
let strLength: number = (someValue as string).length // jsx 只识别该方法