自定义指令 限制input 的输入位数

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>限制input输入的位数</title>
</head>
<body>
      <div id="app">
         <input type="text"   v-split.5="msg"/>
      </div>
</body>
<script src="./node_modules/vue/dist/vue.js"></script>  
<script>
    //设置input 的输入位数
  Vue.directive('split',{
      update(el,bindings,vnode) {
            console.log(bindings);
            let [,len]  = bindings.rawName.split('.');
            console.log(len)
            let ctx = vnode.context;  //msg
            el.addEventListener('input',(e)=>{
                let  val  =  e.target.value.slice(0,len);
                ctx[bindings.expression]=val;
                el.value = val;
            })
            //默认值
            el.value=ctx[bindings.expression];
      },
      bind(el,bindings,vnode) {
           let ctx = vnode.context;  //msg
           let [,len]  = bindings.rawName.split('.');
            el.addEventListener('input',(e)=>{
                let  val  =  e.target.value.slice(0,len);
                ctx[bindings.expression]=val;
                el.value = val;
            })
             //默认值
             el.value=ctx[bindings.expression];
      }

  })
  let vm = new Vue({
      el:"#app",
      data() {
         return {
             msg:'a'
         }
      }
  })
</script>
</html>
 
 
 
 
el,bindings,vnode
 
el表示 html 元素
bindings 表示绑定的元素上的属性
vnode 表示绑定元素的虚拟node
posted @ 2019-09-21 22:36  1点  阅读(698)  评论(0)  编辑  收藏  举报