Question

我有一个事件处理程序，需要访问React组件（this）才能使用this.setState()。删除组件后，我希望事件处理程序被垃圾回收。

我问自己是否有比现有设置更好的方法：

class MyComponent extends React.Component {
    constructor(props) {
        super(props);

        // Preserve this context
        this.handleKeyDown = this.handleKeyDown.bind(this);
    }

    render() {
        return <div></div>;
    }

    handleKeyDown() {
        // this.setState(...);
    }

    componentWillMount() {
        window.addEventListener("keydown", this.handleKeyDown);
    }

    componentWillUnmount() {
        // Clean up
        window.removeEventListener("keydown", this.handleKeyDown);
    }
};

修改

特别是这条线对我来说似乎有些苛刻：

// Preserve this context
this.handleKeyDown = this.handleKeyDown.bind(this);

Answer 1

经过一番讨论（见问题评论）后，人们一致认为这种方式完全没问题：

 enter code here
connection.query('SELECT * FROM departments WHERE manager_id > :id', [110],      {
  splitResults: true, //True to enable to split the results into bulks, each bulk will invoke the provided callback (last callback invocation will have empty results)
  bulkRowsAmount: 100 //The amount of rows to fetch (for splitting results, that is the max rows that the callback will get for each callback invocation)
}, function onResults(error, results) {
  if (error) {
    //handle error...
  } else if (results.length) {
    //handle next bulk of results
  } else {
    //all rows read
  }
});

使用“this”上下文清理keypress事件监听器

1 个答案: