How to avoid calling setTimeout in Apache ECharts SSR

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04-10-2024

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Avoiding setTimeout in Apache ECharts SSR for Seamless Server-Side Rendering

Server-Side Rendering (SSR) with Apache ECharts can significantly enhance the user experience by providing faster initial page loads and improved SEO. However, a common pitfall arises when using setTimeout within ECharts, particularly in SSR scenarios. Let's explore why this presents a challenge and how to overcome it.

The Challenge of setTimeout in SSR

ECharts often leverages setTimeout to handle asynchronous operations, such as animations or data loading. In SSR, where rendering happens on the server, setTimeout behaves differently. It doesn't execute immediately, and the rendered HTML might lack the expected dynamic elements.

Example:

// ECharts configuration using setTimeout for animation
const chart = echarts.init(document.getElementById('chartContainer'));
const options = {
  series: [{
    type: 'line',
    data: [],
    animationDuration: 1000, // animation duration set to 1 second
    animationEasing: 'linear',
  }],
};

// Add data to the chart and start animation after 1 second
setTimeout(() => {
  options.series[0].data = [10, 20, 30];
  chart.setOption(options);
}, 1000);

In SSR, this code won't trigger the animation immediately, as setTimeout would only be executed on the client-side after the page is fully loaded. The user will see a static chart without the intended animation.

Resolving the Issue: Embrace Synchronous Operations

To avoid setTimeout-related issues in SSR, we need to make ECharts operations synchronous. Here are some effective strategies:

1. Pre-Load Data: If the data for your chart is readily available, load it before initializing ECharts. This ensures the chart has all the necessary data from the beginning.

2. Avoid setTimeout for Chart Configuration: Instead of using setTimeout for configuring chart properties, modify the options object directly before initializing ECharts. This ensures all elements are rendered correctly from the start.

3. Use ECharts' Animation Features: ECharts provides dedicated features for animations. Utilize the animationDuration and animationEasing properties within the chart configuration to control animations without relying on setTimeout.

Refactored Example:

// ECharts configuration using synchronous operations
const chart = echarts.init(document.getElementById('chartContainer'));
const options = {
  series: [{
    type: 'line',
    data: [10, 20, 30], // data loaded before initialization
    animationDuration: 1000,
    animationEasing: 'linear',
  }],
};

chart.setOption(options); // chart initialized with data and animation options

Additional Considerations

• CSS Animations: If your animation is entirely CSS-based, you can utilize CSS animations directly within your chart's HTML elements. This allows for client-side animations without requiring setTimeout.
• React and Vue.js: When working with React or Vue.js, consider using libraries like react-echarts or vue-echarts to manage SSR interactions. These libraries provide specific methods for managing ECharts within your framework's context.

By understanding the challenges of setTimeout in SSR and adopting the recommended approaches, you can achieve seamless server-side rendering with ECharts, resulting in a smoother and more efficient user experience.