2022-09-23 Avoid mutating a prop directly since the value will be overwritten whenever the parent component re-renders.

父组件给子组件传值，提示子组件不能直接修改父组件传递过来的值，完整报错：

 Avoid mutating a prop directly since the value will be overwritten whenever the parent component re-renders. Instead, use a data or computed property based on the prop's value. Prop being mutated: "value"

解释：避免直接更改props，因为每当父组件重新渲染时，该值都会被覆盖。而是使用基于props值的数据或计算属性。正在修改的属性：“value”

解决方案：把子组件要修改的值通过$emit返回给父组件，让后者去修改。

this.$emit('value', nValue)