Suspense

Catalyst provides advanced Suspense support with intelligent SSR asset management powered by Vite. The latest version v0.0.2-canary.1 introduces smart code splitting with per-component SSR control and automatic asset categorization.

Installation

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Overview

Catalyst's Suspense implementation runs on Vite's build pipeline and provides:

• Smart Code Splitting: Automatic asset categorization (essential, SSR-enabled, SSR-disabled)
• Per-Component SSR Control: Fine-grained control over server-side rendering
• Intelligent Asset Loading: Essential assets load first, non-essential assets load progressively
• Streaming SSR: Non-blocking server-side rendering with progressive enhancement
• Automatic Asset Deduplication: Prevents loading duplicate resources

The split() Function

Use the split() function instead of React.lazy() for enhanced SSR compatibility and asset management:

Basic Usage

import { split } from "catalyst"

// Basic split with SSR enabled (default)
const LazyComponent = split(() => import("./LazyComponent"))

// With custom fallback
const LazyComponent = split(() => import("./LazyComponent"), {
    fallback: <div>Loading component...</div>
})

// Usage in component
const Home = () => {
    return (
        <div>
            <LazyComponent />
        </div>
    )
}

SSR Control

Control whether components render on the server using the ssr flag:

// Component renders on server (default)
const ServerRenderedComponent = split(() => import("./ServerComponent"), {
    ssr: true,
    fallback: <div>Loading...</div>
})

// Component only renders on client
const ClientOnlyComponent = split(() => import("./ClientComponent"), {
    ssr: false,
    fallback: <div>Client-side only component loading...</div>
})

Real-World Examples

Dashboard with Mixed SSR Strategy:

import { split } from "catalyst"

// Critical above-the-fold content - SSR enabled
const DashboardHeader = split(() => import("./DashboardHeader"), {
    ssr: true,
    fallback: <div className="header-skeleton">Loading header...</div>
})

// Interactive widgets - client-side only for better performance
const InteractiveChart = split(() => import("./InteractiveChart"), {
    ssr: false,
    fallback: <div className="chart-skeleton">Loading chart...</div>
})

// Settings modal - lazy load when needed
const SettingsModal = split(() => import("./SettingsModal"), {
    ssr: false,
    fallback: null // No fallback needed for modals
})

const Dashboard = () => {
    return (
        <div>
            <DashboardHeader />
            <div className="content">
                <InteractiveChart />
                {/* SettingsModal loads only when state changes trigger it */}
                <SettingsModal />
            </div>
        </div>
    )
}

Asset Management

Catalyst automatically categorizes your assets based on how you use split():

Asset Categories

1. Essential Assets: Core app functionality, entry points, shared utilities
2. SSR-Enabled Assets: Components with ssr: true that load during server rendering
3. SSR-Disabled Assets: Components with ssr: false that load only on the client

Loading Strategy

// This happens automatically:
// 1. Essential assets load immediately
// 2. SSR-enabled assets load during server rendering
// 3. SSR-disabled assets load progressively on client

Migration from React.lazy

If you're upgrading from standard React.lazy, here's how to migrate:

Before (React.lazy)

import React, { Suspense, lazy } from "react"

const LazyComponent = lazy(() => import("./LazyComponent"))

const App = () => (
    <Suspense fallback={<div>Loading...</div>}>
        <LazyComponent />
    </Suspense>
)

After (Catalyst split)

import { split } from "catalyst"

const LazyComponent = split(() => import("./LazyComponent"), {
    ssr: true, // or false based on your needs
    fallback: <div>Loading...</div>
})

const App = () => <LazyComponent />

Advanced Patterns

Conditional SSR Based on User Agent

const MobileOptimizedComponent = split(() => import("./MobileComponent"), {
    ssr: true,
    fallback: <div>Loading mobile view...</div>
})

const DesktopComponent = split(() => import("./DesktopComponent"), {
    ssr: true,
    fallback: <div>Loading desktop view...</div>
})

Progressive Enhancement

// Base functionality loads with SSR
const BaseArticle = split(() => import("./BaseArticle"), {
    ssr: true,
    fallback: <div>Loading article...</div>
})

// Enhanced features load client-side
const ArticleInteractions = split(() => import("./ArticleInteractions"), {
    ssr: false,
    fallback: null
})

const ArticlePage = () => (
    <div>
        <BaseArticle />
        <ArticleInteractions />
    </div>
)

Best Practices

1. SSR Strategy

• Enable SSR for above-the-fold content and SEO-critical components
• Disable SSR for highly interactive widgets, client-dependent features
• Use progressive enhancement by layering client-only features over SSR base content

2. Fallback Design

// Good: Meaningful loading states
const Component = split(() => import("./Component"), {
    fallback: <div className="skeleton">Loading content...</div>
})

// Better: Match expected content structure
const Component = split(() => import("./Component"), {
    fallback: (
        <div className="article-skeleton">
            <div className="title-skeleton" />
            <div className="content-skeleton" />
        </div>
    )
})

3. Performance Optimization

// Group related components to reduce chunk fragmentation
const UserProfile = split(() => import("./user/UserProfile"))
const UserSettings = split(() => import("./user/UserSettings"))
const UserActivity = split(() => import("./user/UserActivity"))

Troubleshooting

Components Not Loading on Server

If your component depends on clientFetcher data and fails on the server:

const DataDependentComponent = split(() => import("./DataComponent"), {
    ssr: false, // Disable SSR for client-data dependent components
    fallback: <div>Loading data-driven content...</div>
})

Asset Loading Issues

The build system automatically handles asset categorization. If you experience issues:

1. Check that imports use relative paths or configured aliases
2. Ensure components are properly exported as default exports

Build System Integration

Catalyst's Suspense features integrate with Vite's build system:

• Manifest Categorization Plugin: Automatically categorizes assets during build
• Cache Key Injection Plugin: Optimizes asset tracking and loading
• ChunkExtractor: Intelligently manages asset dependencies during SSR

This integration ensures optimal performance without manual configuration.