1控制台报错
react-dom.production.min.js:32 Uncaught ReferenceError: setState is not defined
at Counter._add (<anonymous>:54:7)
这个是因为setState前面需要加this
2控制台报错
index.js:1 Warning: You provided a `value` prop to a form field without an `onChange` handler. This will render a read-only field. If the field should be mutable use `defaultValue`. Otherwise, set either `onChange` or `readOnly`.
这个是因为我们用的input,没有给他添加onChange事件,给添加上事件就可以了~
3控制台报错
App.js:11 Uncaught TypeError: Cannot read properties of undefined (reading 'setState')
at _usenameChange (App.js:11)
这个是因为this的指向问题造成的,根据上面提示,可以看看是不是方法那用的是普通函数
4控制台报错
Warning: Functions are not valid as a React child. This may happen if you return a Component instead of <Component /> from render. Or maybe you meant to call this function rather than return it.
这个是因为在控制子组件的显示隐藏的时候,调用方法,没有写()
