react相关小技巧

1、咱们在项目中切换路由的时候可能会遇到

Warning: 
setState(...): Can only update a mounted or mounting component. 
This usually means you called setState() on an unmounted component. 
This is a no-op.
Please check the code for the xxx component.

关于react中切换路由时报以上错误，实际的缘由是由于在组件挂载（mounted）以后进行了异步操做，好比ajax请求或者设置了定时器等，而你在callback中进行了setState操做。当你切换路由时，组件已经被卸载（unmounted）了，此时异步操做中callback还在执行，所以setState没有获得值。
最简单也是最有效的方法

componentWillUnmount = () => {
    this.setState = (state,callback)=>{
      return;
    };
}