Experiment: Context driver providing a way to recognise the inherit coupling of state with a view, its metadata and children. A context object is built and extended by each nested component as it is emitted to its parent.

contextDriver.js

export function makeContextDriver(domDriver) {
  return function(context$) {
    const ctx$ = context$.multicast();
    const vtree$ = ctx$.filter(c => c.vtree).map(c => c.vtree);
    const state$ = ctx$.filter(c => c.state).map(c => c.state);
    const metadata$ = ctx$.filter(c => c.metadata).map(c => c.metadata);

    return {
      DOM: domDriver(vtree$),
      state$,
      metadata$
    };
  };
}

export function makeClientContextDriver(domDriver) {
  function setTitle(title) {
    document.title = title;
  }
  return function(context$) {
    const contextDriver = makeContextDriver(domDriver);
    const source = contextDriver(context$);

    source.metadata$
      .filter(m => m.title)
      .map(m => m.title)
      .observe(setTitle);

    return source;
  };
}