Vue初学，数据绑不上

Question

vue.js:515 [Vue warn]: Property or method "name" is not defined on the instance but referenced during render. Make sure to declare reactive data properties in the data option.
(found in root instance)
是哪里出错？

Answer 1

name没有定义,依照楼上的设置一个初始值即可

Answer 2

name 在data那里没有定义。
要这样定义

export default {
    name: 'app',
    data() {
        return {
           name: ''
        }
    },
    ......

Answer 3

奇怪，我在js中明明定义了，但是也是提示这种错误