对vue下点击事件传参和不传参的区别详解

<div id = 'app'>
  <p><button @click = 'test_click1'>{{btn_text1}}</button></p>
  <br>
  <p><button @click = 'test_click2("123")'>{{btn_text2}}</button></p>
 </div>

 <script src="https://cdn.bootcss./vue/2.5.8/vue.min.js"></script>
 <script type="text/javascript">

  var _vm = new Vue({
   data : {
    btn_text1 : '点击1' ,
    btn_text2 : '点击2'
   },
   methods : {
    test_click1 : function (e) {
     console.log('test_click1--------------------------') ;
     console.log(e) ;   
     // 输出结果MouseEvent {isTrusted: true, screenX: 40, screenY: 121, clientX: 40, clientY: 30, …}

     console.log(e.target) ;  // 输出结果<button>点击1</button>
     console.log('test_click1--------------------------') ;
    },
    test_click2 : function (e) {
     console.log('test_click2--------------------------') ;
     console.log(e) ;   // 输出结果123
     console.log(e.target) ;  // 输出结果undefined
     console.log('test_click2--------------------------') ;
    }
   }
  }).$mount('#app');
 </script>