``` <div id="app"> <p v-fontweight="900">aaaa</p> </div> <script> var vm = new Vue({ el: '#app', directives: { 'fontweight': { bind: function(el, binding){ el.style.fontWeight = binding.value } } } }) </script> ``` 指令简写： ``` /* 指令简写: 这个function等同于把代码写到了bind和update中去 */ 'fontsize': function(el, binding){ el.style.fontSize = parseInt(binding.value) + 'px'; } ```