FAQ · JavaScript & SPAs
Can a Screenshot API render JavaScript-heavy SPAs correctly?
Yes. Leading Screenshot APIs run a real Chromium-based headless browser, so React, Vue, Angular, and Svelte apps render exactly as they do for a real user — including client-side routing, data fetching, and dynamic styles.
Why real Chromium matters
Some older or cheaper screenshot services fetch pages with a simple HTTP client — they get the raw HTML source but never execute JavaScript. This means SPAs that fetch their content client-side will appear as empty shells in the screenshot.
SnapshotFlow and other leading APIs use a real headless Chromium process which fully executes JavaScript, handles async data fetching, runs CSS animations, applies web fonts, and renders SVGs — identical to what a visitor sees in Chrome.
Wait strategies to capture fully hydrated pages
The key challenge is knowing when a JavaScript app is done rendering. Use one of these four wait strategies via the wait_for parameter:
| Strategy | Best for |
|---|---|
wait_for=networkidle |
Pages that load data via API calls — waits until no more network requests fire |
wait_for=.my-selector |
Waiting for a specific DOM element (e.g., a loaded chart or a hero image) |
delay=2000 |
Fixed pause for pages with animations or timers |
wait_for=window.__ready===true |
Custom JavaScript expression — most precise for apps you control |
GET https://api.snapshotflow.com/screenshot
?url=https://my-react-app.com/dashboard
&wait_for=networkidleCommon JavaScript rendering issues and fixes
- Loading spinners captured instead of content. Switch from a delay to a
wait_forCSS selector that only appears when data is loaded. - Fonts not rendering. Some custom web fonts require additional load time. Add a short
delay=500after the selector wait. - Charts blank on first render. Chart libraries (Chart.js, D3) animate on load. Use
delay=1000or detect the canvas completion event. - Content behind auth gates showing login screen. Pass session cookies with your API request — see the authenticated pages FAQ.
Capture your SPA today
SnapshotFlow uses real Chromium with all four wait strategies. 200 free screenshots per month — no credit card needed.
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