How to add scroll event in react component

ghz 6months ago ⋅ 118 views

I'm trying to add an onScroll event on a table. This is what I've tried:

componentDidMount() {
    ReactDOM.findDOMNode(this.refs.table).addEventListener('scroll', this.listenScrollEvent);
}

componentWillUnmount() {
    ReactDOM.findDOMNode(this.refs.table).removeEventListener('scroll', this.listenScrollEvent);
}

listenScrollEvent() {
    console.log('Scroll event detected!');
}

render() {
    return (
        <table ref="table">
           [...]
        </table>
    )
}

I tried console.log(ReactDOM.findDOMNode(this.refs.table)) and I'm getting the correct result but scroll event is never fired at all.

Answers

The issue you're facing with adding a scroll event listener to a table component in React can be resolved by ensuring that the event listener setup and teardown are handled correctly within the React component lifecycle. Here’s a refined approach to achieve this:

Approach Using React Refs and Event Listeners

  1. Using Refs: Utilize React refs to access the DOM node of the table directly.

  2. Event Listener Setup: Set up the scroll event listener in componentDidMount().

  3. Event Listener Removal: Remove the event listener in componentWillUnmount() to prevent memory leaks.

Here’s how you can modify your component:

import React from 'react';
import ReactDOM from 'react-dom';

class ScrollableTable extends React.Component {
  constructor(props) {
    super(props);
    this.tableRef = React.createRef();
  }

  componentDidMount() {
    this.tableRef.current.addEventListener('scroll', this.listenScrollEvent);
  }

  componentWillUnmount() {
    this.tableRef.current.removeEventListener('scroll', this.listenScrollEvent);
  }

  listenScrollEvent = (event) => {
    console.log('Scroll event detected!', event);
    // Additional logic for handling scroll event
  };

  render() {
    return (
      <div style={{ overflow: 'auto', maxHeight: '400px' }}>
        <table ref={this.tableRef}>
          {/* Your table content */}
          <thead>
            <tr>
              <th>Header 1</th>
              <th>Header 2</th>
              <th>Header 3</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td>Data 1</td>
              <td>Data 2</td>
              <td>Data 3</td>
            </tr>
            {/* Additional rows */}
          </tbody>
        </table>
      </div>
    );
  }
}

export default ScrollableTable;

Explanation:

  • Ref Creation:

    • Use React.createRef() to create a ref (this.tableRef) that will be attached to the <table> DOM element.

  • Event Listener Setup (componentDidMount):

    • In componentDidMount(), access the DOM node using this.tableRef.current and add a scroll event listener (addEventListener) that calls this.listenScrollEvent when the table is scrolled.

  • Event Listener Removal (componentWillUnmount):

    • In componentWillUnmount(), remove the scroll event listener (removeEventListener) to clean up and prevent memory leaks when the component is unmounted.

  • Handling Scroll Events:

    • Define listenScrollEvent as a class method to handle the scroll events. This method can access the event object (event) and perform any additional logic based on the scroll behavior.

Notes:

  • Styling and Layout: Ensure that the <table> element is within a container (<div style={{ overflow: 'auto', maxHeight: '400px' }}> in this example) that enables scrolling (overflow: 'auto' and maxHeight).

  • Ref Usage: Always use ref={this.tableRef} to attach the ref to the component you want to interact with via DOM methods or event listeners.

This approach ensures that the scroll event listener is correctly set up and removed during the component lifecycle, addressing the issue of the scroll event not firing as expected.

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