javascript - 如何在渲染 react native 中设置状态

Question

当我想在渲染生命周期中设置状态时，它给了我这个错误

Warning: Cannot update during an existing state transition (such as within render or another component's constructor). Render methods should be a pure function of props and state; constructor side-effects are an anti-pattern, but can be moved to componentWillMount.

changeInitial(){
   this.setState({initialLoad: false});
}

render() {
    if (this.state.initialLoad) {
        Animated.timing(this.state.listPosition, {
            toValue: 350,
            duration: 2000,
        }).start(() => this.changeInitial());
    }
 }

Answer 1

您不应在 render() 方法内使用 setState()，因为它会在渲染器内触发重新渲染，从而引发错误。更好的方法是在 componentDidMount() 方法内部，如下所示:

changeInitial(){
   this.setState({initialLoad: false});
}
componentDidMount(){
    if (this.state.initialLoad) {
       Animated.timing(this.state.listPosition, {
           toValue: 350,
           duration: 2000,
       }).start(() => this.changeInitial());
    }
}
render() {
    // Your component template here
}