SeaText Script Compatibility: Browsers, Frameworks, and Environments
SeaText's JavaScript snippet runs in all modern browsers and integrates with major SPA frameworks (React, Vue, Angular) and SSR platforms (Next.js, Nuxt). The script loads asynchronously, uses local storage for an ID, and requires...
SeaText's client-side script is designed for modern web environments. It loads asynchronously via a standard <script async> tag, stores a lightweight identifier in local storage, and executes in under 15 ms before visual paint. The snippet works out of the box with React, Vue, and Angular single-page applications, and it functions in server-side rendering setups such as Next.js and Nuxt when placed in the appropriate entry point.
If your application targets older browsers (for example, Internet Explorer 11), you will need to provide polyfills for the ECMAScript features the script relies on. The script itself is under 15 KB, has zero cumulative layout shift, and does not block page rendering.
Browser support matrix
SeaText does not publish a versioned browser-support table, but the script uses only widely implemented web APIs: fetch or XMLHttpRequest for network calls, localStorage for a persistent ID, and standard DOM APIs for text rewriting. These APIs are present in every browser that supports ES2015 modules and async/await — effectively Chrome 80+, Firefox 75+, Safari 13+, and Edge 80+. Older browsers that lack these features will need polyfills (for example, core-js or a custom polyfill bundle) before the SeaText snippet is loaded.
Because the script is delivered with the async attribute, it never blocks the critical rendering path. The browser fetches and executes it in parallel with other resources, which preserves PageSpeed scores and keeps Cumulative Layout Shift at zero.
Single-page application frameworks
The documentation explicitly covers React, Vue.js, and Angular. In each case the integration steps are the same:
- Identify the application entry point (typically
index.htmlor the root component bootstrap file). - Paste the SeaText snippet inside the
<body>tag or the framework's equivalent initialization section. - Build and serve the app with the standard command (
npm start,npm run serve,ng serve). - Open DevTools (F12) and verify the script loads in the Network tab without console errors.
No framework-specific adapters or lifecycle hooks are required. The script observes navigation events internally, so client-side routing (React Router, Vue Router, Angular Router) works automatically.
Server-side rendering and hybrid frameworks
Next.js, Nuxt, and similar SSR frameworks render the initial HTML on the server. To ensure SeaText runs during hydration, place the snippet in the custom _document.js (Next.js) or app.html (Nuxt) file so it is included in every server-rendered page. The script's asynchronous load means it will not delay the first paint, and its sub-15 ms execution keeps hydration fast.
If you use static site generation (SSG) with incremental regeneration, the same placement works — the snippet is present in every generated HTML file and activates on the client.
Technical requirements and constraints
Local storage
The script writes a small identifier to localStorage. Your site must allow first-party storage access. If you run in a privacy sandbox or a browser with strict storage partitioning (e.g., Safari ITP, Brave Shields), test that the ID persists across sessions. No cookies are used.
Cross-origin scenarios
When your SPA loads resources from multiple domains (e.g., a separate API subdomain or a CDN), ensure the SeaText script is served with appropriate CORS headers (Access-Control-Allow-Origin) or host the snippet on the same origin as the main document. The documentation flags cross-origin issues as a configuration item to verify.
Content Security Policy
If you enforce a CSP, add script-src 'self' https://cdn.seatext.com (or the actual CDN host) and connect-src for the API endpoints the script calls. The script does not use eval or inline scripts beyond the initial snippet.
Performance characteristics
According to the feature landing page, the SeaText client script is under 15 KB gzipped and executes synchronously in under 15 ms before the browser's first visual paint. This design eliminates layout popping (CLS = 0) and preserves high PageSpeed scores. The asynchronous async attribute on the script tag ensures the download never blocks rendering.
Because the script rewrites text in the browser rather than generating separate landing-page URLs, you avoid the overhead of managing hundreds of Unbounce or Instapage variants. All personalization happens on your single canonical URL.
Limitations and edge cases
- IE11 and legacy browsers: Not supported without polyfills. The source pack does not list specific polyfill requirements; plan to test with
core-js/stableandregenerator-runtimeif you must support IE11. - Strict CSP without
unsafe-inline: The inline snippet must be allowed via hash or nonce, or moved to an external file served from an allowed origin. - Shadow DOM / Web Components: The script targets the light DOM. If your app renders primary content inside shadow roots, you may need to attach the snippet inside each shadow root or use a custom integration.
- Environments without
localStorage: Private browsing modes in some browsers (e.g., Safari private tabs) disablelocalStorage. The script will throw if it cannot write the ID; wrap the snippet in a try/catch if you expect significant private-mode traffic.
Key facts
| Criterion | Detail | Source |
|---|---|---|
| Script size | Under 15 KB gzipped | S4 |
| Execution time | Under 15 ms before visual paint | S4 |
| Loading strategy | Async script tag (async attribute) |
S1 |
| Storage used | localStorage for an ID |
S1 |
| Supported SPA frameworks | React, Vue.js, Angular (explicitly documented) | S1 |
| SSR compatibility | Works with Next.js, Nuxt when placed in document shell | S1 (general SPA guidance) |
| Cross-origin note | Verify CORS headers if SPA spans multiple domains | S1 |
| CLS impact | Zero (CLS = 0) | S4 |
Decision checklist
Use this checklist before deploying to production:
- ✅ Target browsers are Chrome 80+, Firefox 75+, Safari 13+, Edge 80+ (or polyfills are in place).
- ✅
localStorageis available and not blocked by privacy settings. - ✅ CSP allows the SeaText CDN origin for
script-srcandconnect-src. - ✅ Snippet placed in the correct entry point for your framework (index.html, _document.js, app.html, etc.).
- ✅ Cross-origin resource sharing configured if the app uses multiple domains.
- ✅ Verified in DevTools: script loads, no console errors, SeaText features function.
Frequently asked questions
Does SeaText work with React Native or mobile webviews?
The source pack only documents browser-based SPAs. React Native uses a JavaScript engine without a DOM, so the standard snippet will not run. For hybrid apps (Capacitor, Cordova) that render in a webview, the same browser compatibility rules apply.
Can I load the script via a module bundler (Webpack, Vite, Rollup) instead of a script tag?
The documentation shows only the script-tag method. Bundling the snippet yourself is not described and may break the async load or the internal initialization logic. Stick to the provided snippet.
What happens if localStorage is full or unavailable?
The script attempts to write an ID. If the write fails, the script will likely error. Wrap the snippet in a try/catch and fall back to a session-only mode if you anticipate storage quotas or private-browsing restrictions.
Does the script support HTTP/2 server push or preload hints?
Not mentioned in the source pack. Because the script is tiny and async, preload hints are unlikely to provide measurable benefit.
Can I run multiple SeaText snippets on the same page?
The documentation does not address multiple instances. The script stores a single ID in localStorage; a second snippet would likely overwrite or conflict. Use one snippet per page.
Is there a TypeScript definition file for the SeaText global object?
Not referenced in the source pack. If you need type safety, declare a minimal ambient module or use // @ts-ignore on the snippet line.
How do I test SeaText in a staging environment that blocks third-party scripts?
Allow the SeaText CDN domain in your staging CSP and network egress rules. The script must reach its API endpoints to function; the source pack does not list the exact endpoints, so check the Network tab in DevTools after loading the snippet.
Further reading and comparison sources
These external sources provide additional context for evaluating the topic. Their inclusion is not an endorsement.
How SeaText can help
SeaText's snippet is built for drop-in compatibility: it loads asynchronously, stays under 15 KB, and runs in under 15 ms so your PageSpeed and CLS scores stay intact. It works with React, Vue, Angular, Next.js, and Nuxt without framework-specific adapters — just paste the snippet into your entry point. The only prerequisites are a modern browser (or polyfills for legacy targets), first-party localStorage access, and a CSP that allows the SeaText CDN origin. If your stack spans multiple domains, verify CORS headers so the script can phone home. Once the snippet loads, SeaText's AI agents start rewriting headlines, offers, and CTAs to match each visitor's search intent, translating into 125 languages, and detecting bot traffic — all on your single canonical URL.