vue源码思考

vue data属性的双向绑定

json是存在对象索引的。 就是说data = {'attr1': 1}; vm={'data': data}; //1) data.attr1=2; => vm.data will be {attr1: 2}.//2) vm.data.attr1 = 2, data will be{ attr:2}

question is data={attr1:1}; vm = new vue({ data: data }) . vm.att1 == 1. how can we implement ths?