<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.com/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>