function linkState(component, key, eventPath) {
  let path = key.split('.'), cache = component.__lsc || (component.__lsc = {});

  return cache[key + eventPath] || (cache[key + eventPath] = function(e) {
           let t = e && e.target || this, state = {}, obj = state,
               v = typeof eventPath === 'string' ?
               delve(e, eventPath) :
               t.nodeName ? (t.type.match(/^che|rad/) ? t.checked : t.value) :
                            e,
               i = 0;
           for (; i < path.length - 1; i++) {
             obj = obj[path[i]] ||
                 (obj[path[i]] = !i && component.state[path[i]] || {});
           }
           obj[path[i]] = v;
           component.setState(state);
         });
}