vue2.0自定义指令的使用方法

感觉2.0好坑啊,自定义指令和1.0完全不一样,并且文档写得也不太清晰,下面是我写得一个demo,希望帮助大家更好地理解自定义指令

<!DOCTYPE html>
<html >

<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <script src="https://unpkg.com/vue/dist/vue.js"></script>
  <!-- <script type="text/javascript" src="vue.js"></script> -->
</head>

<body>
  <div >
    <p v-demo="{color:'red'}">红色文字</p>
    <input type="text" name="" v-focus>
  </div>
  <script type="text/javascript">
  window.onload = function() {
      // 全局指令
    Vue.directive('demo',{
            bind:function(el,val){
                el.style.color = val.value.color
            }
        });
        Vue.directive('focus',{
            inserted: function(el,val) {
            el.focus()
        }
        });
        // 局部指令
    var app = new Vue({
      el: '#box',
      directives: {
        demo: {
          bind: function(el, val) {
            el.style.color = val.value.color
          }
        },
        focus: {
            inserted: function(el,val) {
                el.focus()
            }
        }
      }
    });
  }
  </script>
</body>

</html>