vuejs uppercase directive

vue-uppercase.js

Vue.directive("uppercase", {
  twoWay: true,
  // TODO: unbind
  unbind: () => {},
  bind: function (el, binding, vnode) {
    const findVModelName = vnode => {
      try {
        // https://forum.vuejs.org/t/solved-how-can-you-update-the-v-model-from-a-custom-directive-in-vue-2/2275
        return vnode.data.directives.find(o => {
          return o.name === "model";
        }).expression;
      } catch (error) {
        error.message = `Unable to find v-model directive at ${
          vnode.tag
        } tag. Please specify the expression: v-uppercase='obj.prop'`;
        throw error;
      }
    };

    const funcByName = (functionName, context, value) => {
      // https://stackoverflow.com/a/359910/8801075
      var namespaces = functionName.split(".");
      var func = namespaces.pop();
      for (var i = 0; i < namespaces.length; i++)
        context = context[namespaces[i]];
      return (context[func] = value);
    };

    var expression = binding.expression ?
      binding.expression :
      findVModelName(vnode);
    vnode.context.$watch(expression, {
      //deep: true, // ?
      immediate: true,
      handler(newVal) {
        if (newVal) {
          return funcByName(
            expression,
            vnode.context,
            newVal.toString().toLocaleUpperCase()
          );
        }
      }
    });
  }
});