实现 readonly 功能

单测

//readonly.spec.ts
import { readonly } from "../readonly"

it('happy path', () => {
    // not set
    const original = { foo: 1, bar: 2 }
    const wrapped = readonly(original)
    expect(wrapped).not.toBe(original)
    expect(wrapped.bar).toBe(2)
    wrapped.foo = 2
    // set 后不会更改
    expect(wrapped.foo).toBe(1)
})

//readonly.ts
export function readonly(raw) {
    return new Proxy(raw, {
        get(target, key, receiver) {
            const res = Reflect.get(target, key, receiver)
            return res
        },
        set() {
            return true
        },
    })
}