value.to( object, keyPath )

In the example below, a keyObservable is created that is one-way bound to the value at outer.inner.key. When keyObservable.value changes, outer.inner.key is updated, but changes to outer.inner.key do not update keyObservable.value.

import {DefineMap, value} from "can";

const outer = new DefineMap({
  inner: {
    key: "hello"
  }
});

const keyObservable = value.to(outer, "inner.key");

keyObservable.value = "aloha";
console.log( outer.inner.key ) //-> "aloha"