js： 类型注解 flow 弱类型引起的问题

测试地址

const hello : string = "Hello World!"
console.log(hello)


let arr: number[] = [1,2,3]
console.log(arr)

let obj: {
 name: string,
	 age: number,
		 sex?:  number
} = {
name: 'zs',
	age: 25

}

let temp : undefined=undefined
let temp2 
console.log(temp)
console.log(temp2)



let tube: [number, string] = [1,'2']

function fn(a:number, b: number, callback: (number) => {}): number {
	callback && callback(a)
	return a+b
}

let flag: Boolean = true
	
	
	const a: 'foo'='foo'
	let type: 'success'|'warning'|'danger' = 'success'
	type = 'warning'
	const b: string|number =  'string'
	
	// let gender: ?number = undefined
	// 等价于
	// let gender: number | null | void = undefined
	

// any和mixed可以是任意类型，但是mixed是强类型使用某个类型的方法必须先typeof做下类型判断
	function passMixed(value:mixed) {
		if(value==='number') return value * value
	}
	
	function passAny(value: any) {
		value.substr(1)
		value * value
	}