i18n typescript try

i18n-try.js

const locale = {
    "en-us": {
        greetings: {
            hello: "Hello {{user}} and {{user}}",
            goodMorning: "Good morning"
        },
        cat: {
            "one": "% cat",
            "many": "% cats"
        },
        name: "name",
        bye: {
            goodBye: "Good bye"
        }
    },
    "fr-be": {
        greetings: {
            hello: "Bonjour {{user}}",
            goodMorning: "Bon matin"
        },
        cat: {
          "one": "% chat",
            "many": "% chats"
        },
        name: "nom",
        bye: {
            goodBye: "Au revoir"
        }
    }
}

type LocaleMap = typeof locale
type LocaleName = keyof LocaleMap
type Locale = LocaleMap[LocaleName]

type PathInfo<T extends Record<string, any>> = keyof {
    [K in keyof T as (T[K] extends string ? K : T[K] extends Record<string, any> ? `${K & string}.${PathInfo<T[K]> & string}` : never)]: any
}

const replace = (str: string, param: string | Record<string, string>) => {
    if (typeof param === 'string') {
        return str.replace(/%/g, param);
    }
    return Object.entries(param).reduce((_, [key, value]) => {
        return str.replace(new RegExp(`{{${key}}}`, "g"), value);
    }, str);
}

const i18n = (lang: LocaleName) => (key: PathInfo<Locale>, param?: string | Record<string, string>): string => {
    const path = key.split(".");
    let current: any = locale[lang];
    for (const k of path) {
        current = current[k];
        if (current === undefined) break;
    }

    if (typeof current === 'string') {
        return param ? replace(current, param) : current;
    }
    throw new Error("Invalid i18n key.")
}

const t = i18n("en-us")

// console.log(t("greetings.hello", { user: 'Guillaume' }))
console.log(t("cat.one", "0"))