Data and Methods
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title></title> <script src="vue.js" type="text/javascript" charset="utf-8"></script> </head> <body> <div id="app"> {{a}} </div> <script type="text/javascript"> var data = { a : 1 }; var vm = new Vue({ el : "#app", data : data }); vm.$watch('a', function(newVal, oldVal){ console.log(newVal, oldVal); }) vm.$data.a = "test...." </script> </body> </html>