React SSR：防止客户端呈现在服务器上呈现的组件

Question

I'm new to React. I'm building a site with react, react router4, react redux, etc., in which few components get rendered on the server (mostly fetching data using API calls and display them). Now my question is if I render component on the server and send rendered HTML to the client, it again gets rendered on the client (makes an API call), which I need to prevent.

I don't want to render component again if it's already rendered on the server. How can I achieve this?

Thanks

Satish

Answer 1

I have a similar problem. I have a large table (5000 rows) rendered on the server. i don't want to send the data to the client twice (in HTML and JSON form) I came up with this solution/hack.

Before rendering the table rows, the component first checks the DOM to see if a component exists with the same id (which if pre-rendered server-side will exist), if it does then it extracts the HTML and uses that directly via dangerouslySetInnerHTML .

 renderTable() {
    debug('render table');
    const id = 'table-body';
    const html = this.getExistingHtml(id);

    if (html) {
      return <tbody id={ id } dangerouslySetInnerHTML={{ __html: html }} />;
    }

    return <tbody id={ id }>{ this.renderItems() }</tbody>;
  }

  getExistingHtml(id) {
    if (typeof document === 'undefined') return;
    const node = document.getElementById(id);
    return node && node.innerHTML;
  }

  renderItems() {
    debug('render items');
    return this.props.items.map(({ name, url }) => {
      return (
        <tr>
          <td>
            <a href={ url }>
              <div>{ name }</div>
            </a>
          </td>
        </tr>
      );
    });
  }

  shouldComponentUpdate() {
    return false;
  }

I've also coupled this with shouldComponentUpdate to prevent any renders after the initial mount.

Answer 2

You may use hydrate from 'react-dom'

https://reactjs.org/docs/react-dom.html#hydrate