Vue directive中修改v-model值

 Vue.directive("custom", {
  bind: function(element, binding, vnode) {
    $(element).on("click", function() {
      vnode.context[binding.expression] = false; // sync binding.value = false;
    });
  }
});

 // 这个函数是从vue.js源码中复制的，方便我们手动触发事件
function trigger(el, type) {
    var e = document.createEvent("HTMLEvents");
    e.initEvent(type, true, true);
    el.dispatchEvent(e);
  }
 Vue.directive("custom", {
  bind: function(element, binding, vnode) {
    $(element).on("focus", function() {
       element.value = 'FOCUS';
       trigger(element, "input");
    });
   }
});