let providerHandler = {
    get: async(target, name) => {
        console.log('load someting from remote...')
        return new Promise( (res, rej) => {
            setTimeout(() => res(42), 4200)
        })
    },
    set: function (obj, prop, value) {
        return new Promise((res, rej) => {
            console.log('save someting remotely...')
            setTimeout(() => res(true), 1000)
        })
    }
}

let recieverHandler = {
    get: async (target, name) => {
        if (target.prop instanceof Promise) {
            return target.prop.then(res => target[name] = res)
        } else {
            return target[name]
        }
    },
    set: function (obj, prop, value) {
        obj[prop] = value
    }
}

async function main() { 
    let dynrecv = new Proxy({}, recieverHandler)
    let dynprov = new Proxy({}, providerHandler)
    
    dynrecv.prop = await dynprov.prop   // await it here
    console.log(await dynrecv.prop)

    dynrecv.another = dynprov.another   // direct assign here, no await
    console.log(await dynrecv.another)
       
    await dynprov.setme("value")        // store someting remotely.
                                        // it's up to u to decide await or not
}

main()