type
type 也可以来进行约束变量类型，类似于interface
type 的使用
ts
type user = {
name: string
age: number
}
type name = string
type fn = (a: number, b: number) => void
type 的继承
ts
type name = {
name: string
}
type age = {
age: number
}
type user = name &
age & {
sayHello(): string
}