CODEWITHSUNDEEP
reactjsthymeleafserver-side-rendering
Sebastian Ullrich
Sebastian Ullrich

Reputation: 1047

Prevent React from re-render partial SSR content on hydrate

How can I prevent SSR content from re-rendered in the clients browser on React.hydrate(...)?

My Workflow

In my current project, I render a bunch of React components during my build process via ReactDomServer.renderToString(...). The result of this rendering will be used as a Thymeleaf fragment. The SSR DOM contains several th:text attributes for internalization:

Brief example

This is my component:

import React from "react";

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

    shouldComponentUpdate() {
        return false;
    };

    render() {
        return (
            <span {...{ 'th:text': `#{${this.props.i18n}}` }}>
                {this.props.i18n}
            </span>
        );
    }
}

export default WdbThym;

This is an example usage of WdbThym:

<WdbThym i18n="general.hello_world" />

This is what ReactDomServer.renderToString(...) creates:

<span th:text="#{general.hello_world}">general.hello_world</span>

This is what Thymeleaf renders and dispatches to the client:

<span>Hello World!</span>

This is what React.hydrate renders:

<span th:text="#{general.hello_world}">general.hello_world</span>

How can I prevent the initial rendering on React.hydrate(...) for the above mentioned Component?

Upvotes: 4

Views: 5175

Answers (1)

Sebastian Ullrich
Sebastian Ullrich

Reputation: 1047

As @estus reported, https://github.com/facebook/react/issues/8017 solved this problem.

I've created a slightly more complex sample to reproduce the given advice:

DOM

<div id="root">
  <div class="App">
    <h1>THIS IS SSR CONTENT</h1>
    <p>Current Time: 2019-01-27T08:00:00.000Z</p>
    <p>Hello World from Thymeleaf (SSR)</p>
  </div>
</div>

React

class CsrComponent extends React.Component {
  state = { currentTime: "" };

  componentDidMount = () => {
    setInterval(() => {
      this.setState({ currentTime: new Date().toISOString() });
    }, 1000);
  };

  render() {
    return <p>Current Time: {this.state.currentTime}</p>;
  }
}

class SsrComponent extends React.Component {
  render() {
    return (
      <p
        dangerouslySetInnerHTML={{ __html: "" }}
        suppressHydrationWarning
        {...{ "th:text": `#{${this.props.i18n}}` }}
      />
    );
  }
}

class App extends React.Component {
  render() {
    return (
      <div className="App">
        <h1>THIS IS SSR CONTENT</h1>
        <CsrComponent />
        <SsrComponent i18n="general.hello_world" />
      </div>
    );
  }
}

Hydrating

const rootElement = document.getElementById("root");
ReactDOM.hydrate(<App />, rootElement);

This given example is also available at https://codesandbox.io/s/o5171l2v59

Upvotes: 4

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