| 1 | --- |
| 2 | title: Preload Based on User Intent |
| 3 | impact: MEDIUM |
| 4 | impactDescription: reduces perceived latency |
| 5 | tags: bundle, preload, user-intent, hover |
| 6 | --- |
| 7 | |
| 8 | ## Preload Based on User Intent |
| 9 | |
| 10 | Preload heavy bundles before they're needed to reduce perceived latency. |
| 11 | |
| 12 | **Example (preload on hover/focus):** |
| 13 | |
| 14 | ```tsx |
| 15 | function EditorButton({ onClick }: { onClick: () => void }) { |
| 16 | const preload = () => { |
| 17 | if (typeof window !== 'undefined') { |
| 18 | void import('./monaco-editor') |
| 19 | } |
| 20 | } |
| 21 | |
| 22 | return ( |
| 23 | <button |
| 24 | onMouseEnter={preload} |
| 25 | onFocus={preload} |
| 26 | onClick={onClick} |
| 27 | > |
| 28 | Open Editor |
| 29 | </button> |
| 30 | ) |
| 31 | } |
| 32 | ``` |
| 33 | |
| 34 | **Example (preload when feature flag is enabled):** |
| 35 | |
| 36 | ```tsx |
| 37 | function FlagsProvider({ children, flags }: Props) { |
| 38 | useEffect(() => { |
| 39 | if (flags.editorEnabled && typeof window !== 'undefined') { |
| 40 | void import('./monaco-editor').then(mod => mod.init()) |
| 41 | } |
| 42 | }, [flags.editorEnabled]) |
| 43 | |
| 44 | return <FlagsContext.Provider value={flags}> |
| 45 | {children} |
| 46 | </FlagsContext.Provider> |
| 47 | } |
| 48 | ``` |
| 49 | |
| 50 | The `typeof window !== 'undefined'` check prevents bundling preloaded modules for SSR, optimizing server bundle size and build speed. |
| 51 |