let a: unknown;
if (typeof a === 'number') {
let b = a + 1
}
if (typeof a === 'string') {
let b = a.toUpperCase()
}
function hello_void() {
console.log('hi')
}
const my_void = hello_void()
my_void.toUpperCase()
function hello_never(): never {
console.log('sorry')
}
function hello_never2(): never {
throw new Error("sorry")
}
function hello_never3(name: string | number) {
if (typeof name === "string") {
name
} else if (typeof name === "number") {
name
} else {
name
}
}
배움출처: https://nomadcoders.co/typescript-for-beginners/lobby