<!DOCTYPE html> <html lang="en" xmlns:th="http://www.w3.org/1999/xhtml"> <head> <script src="../static/js/vue.js"></script> </head> <body> <div id="app"> {{ a }} {{ b }} </div> <script type="text/javascript" > var data = {a : 'a',b: 'b'} var vm = new Vue({ el: '#app', data: data, updated: function () { console.log("updated") } }); vm.a = "new data vue" vm.a == data.a vm.$watch('a',function (newVal,oldVal) { console.log(newVal,oldVal); }); setTimeout(function () { vm.$data.b = "new data vue b" },3000); vm.$data.a = "new data vue $" console.log(vm.$el == document.getElementById('app')) </script> </body> </html>