React lazy load/infinite scroll solutions

Question

It took me a while to figure out how to lazy load images using the excellent React Lazyload component.

The demo lazy loaded images on scroll but when testing I could not get the same behavior.

The culprit was overflow: auto; which conflicted with the component working as intended.

What is the best way to lazy load large image gallery/slideshows in React?

React Lazyload (Really liking this component but want to investigate others)

React Virtualized (Seems heavy but feature-rich)

React Infinite (Higher barrier to entry due to complexity)

React Lazylist (Straight-forward but not sure if optimal for images)

Others...?

I have a universal/isomorphic application so some of the above will break due to window object unable to be used on the server.

Answer 1

If you want a simpler lazy load solution and not have to use other people's packages/code, try using the IntersectionObserver API.

https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API

I wrote a Medium article on how to use it to lazy load images in a React component (implementation is essentially the same with vanilla JS).

https://medium.com/@parkjoon94/lazy-loading-images-intersectionobserver-8c5bff730920

You only really need this part of the code (snippet from above article):

this.observer = new IntersectionObserver(
  entries => {
    entries.forEach(entry => {
      const { isIntersecting } = entry;
      if (isIntersecting) {
        this.element.src = this.props.src;
        this.observer = this.observer.disconnect();
      }
    });
  }, {}
);

Answer 2

import React from "react";
import PropTypes from "prop-types";
import axios from "axios";
import InfiniteScroll from "react-infinite-scroller";
const styles = theme => ({
  root: {
    textAlign: "center",
    paddingTop: theme.spacing.unit * 20
  }
});

class Parent extends React.Component {
  state = {
    allposts: [],
    posts: [],
    hasMore: true,
    curpage: 0,
    pagesize: 30,
    totalPage: 0,
    total: 0
  };

  componentDidMount() {
    axios.get("https://jsonplaceholder.typicode.com/posts").then(res => {
      let curpage = this.state.curpage;
      let posts = res.data.slice(
        curpage * this.state.pagesize,
        (curpage + 1) * this.state.pagesize
      );
      this.setState({
        allposts: res.data,
        posts: posts,
        total: res.data.length,
        totalPage: Math.ceil(res.data.length / this.state.pagesize)
      });
    });
  }

  loadmoreItem() {
    if (this.state.curpage + 1 < this.state.totalPage) {
      let curpage =
        this.state.curpage < this.state.totalPage
          ? this.state.curpage + 1
          : this.state.curpage;
      let posts = this.state.allposts.slice(
        0,
        (curpage + 1) * this.state.pagesize
      );
      this.setState({ posts: posts, curpage });
    } else {
      this.setState({ hasMore: false });
    }
  }

  render() {
    if (this.state.posts.length === 0) return <h1>loading...</h1>;
    else {
      console.log(this.state);
      return (
        <div>
          <Table
            hasMore={this.state.hasMore}
            posts={this.state.posts}
            loadmoreItem={this.loadmoreItem.bind(this)}
          />
        </div>
      );
    }
  }
}

export default Parent;

const Table = props => {
  console.log("props: ", props);
  return (
    <React.Fragment>
      <div style={{ height: "400px", overflow: "auto" }}>
        <InfiniteScroll
          pageStart={0}
          loadMore={props.loadmoreItem}
          hasMore={props.hasMore}
          loader={
            <div className="loader" key={0}>
              Loading ...
            </div>
          }
          useWindow={false}
          threshold={350}
        >
          <table>
            <tr>
              <th>id</th>
              <th>title</th>
              <th>body</th>
            </tr>
            {props.posts.map(item => {
              return (
                <tr>
                  <td>{item.id}</td>
                  <td>{item.title}</td>
                  <td>{item.body}</td>
                </tr>
              );
            })}
          </table>
        </InfiniteScroll>
      </div>
      <button onClick={props.loadmoreItem}>next</button>
    </React.Fragment>
  );
};

check live example here

https://codesandbox.io/s/x228lmm90q