Warning: Can't call setState on a component that is not yet mounted.

Question

啊老师您好，Header.class.tsx 里类 HeaderComponent 的构造函数调用了 store.subscribe(this.handleStoreChange);，而
handleStoreChange 函数里又调用了 setState:

		this.setState({
			language: storeState.language,
			languageList: storeState.languageList,
		});

这会在浏览器开发者工具的 console 里面引起警告：

Warning: Can’t call setState on a component that is not yet mounted. This is a no-op, but it might indicate a bug in your application. Instead, assign to this.state directly or define a state = {}; class property with the desired state in the HeaderComponent component.

请问要怎么处理呢？

我把 store.subscribe(this.handleStoreChange);提出来放到 componentDidMount() 里面，警告就消失了，请问这样是否规范呢？

	componentDidMount() {
		store.subscribe(this.handleStoreChange);
	}

Answer 1

阿莱克斯刘 2021-09-07 03:46:20

你的改动合乎规范，而课程为了讲解方便反而不符合规范。不过，也不用太在意，因为在真实项目中，我们一般都不会直接使用订阅模式，而是通过react-redux来订阅store。