Debugging SeaText Script Loading: Silent Failures When Console Shows No Errors
When the SeaText script loads without console errors but features don't activate, verify that SeaText.init() was called with correct configuration, confirm target elements exist in the DOM, check that the current user matches targeting...
Immediate Diagnostic Steps
Start with these four checks in order. Each takes less than a minute and resolves the majority of silent failures.
- Confirm SeaText.init() executed. Open the browser console and type
typeof SeaText !== 'undefined'. If it returnsfalse, the script never loaded or the global was overwritten. Iftrue, runSeaText.initto see whether the function exists and what parameters it expects. - Verify the configuration object. The init call must include a valid
projectIdand any requiredscopeortargetingfields. A missing or malformedprojectIdcauses the script to idle without throwing. - Check DOM readiness for target elements. SeaText rewrites text nodes that match its selectors. If your SPA renders those nodes after SeaText runs (common in React
useEffector Vuemounted), the rewrite pass finds nothing. Wrap the init call in a mutation observer or framework lifecycle hook that fires after the target markup exists. - Enable debug mode. Call
SeaText.debug(true)beforeinit(). This logs internal decisions — targeting evaluation, variant selection, rewrite attempts — to the console without affecting production behavior.
Why Silent Failures Happen
SeaText loads asynchronously with the async attribute to protect page speed. The script registers a global SeaText object and waits for init(). If your code calls init() before the script finishes loading, the call is queued and executed later — but only if the queue mechanism is intact. A minifier or bundler that renames globals can break the queue. Similarly, Content Security Policy (CSP) directives that block eval or inline scripts may allow the script to load but prevent the rewrite engine from executing.
Single-page applications add another failure mode: the initial HTML contains no SeaText-targetable content. The script loads, init() runs, finds nothing, and exits cleanly. When the route changes and new content mounts, SeaText does not automatically re-scan unless you call SeaText.refresh() or re-initialize.
SPA-Specific Loading Patterns
The SeaText documentation for SPAs recommends placing the snippet in index.html inside the <body> tag, then building and serving the app normally. After the first load, inspect the Network tab for the SeaText script (status 200, correct MIME type) and the Console for any warnings. The docs then say: "Ensure that the SEATEXT AI features are functioning as expected within your SPA." This implies a manual verification step — there is no automatic health ping.
For React, Vue, and Angular the same snippet works, but each framework mounts the root component at a different moment. If you initialize SeaText in a top-level useEffect with an empty dependency array, it runs once on mount. If your translated components mount later (lazy-loaded routes, code-split chunks), you must call SeaText.refresh() after they appear.
Targeting Rules and User Matching
SeaText applies variants only when the visitor satisfies targeting conditions: UTM parameters, referrer, geolocation, cookie flags, or custom JavaScript predicates. If your test session doesn't match any active rule, the script loads, evaluates targeting, finds no match, and does nothing — silently. Use SeaText.debug(true) to see the targeting evaluation log. It prints each rule, the visitor's value, and the pass/fail result.
Common mismatches:
- Testing from an IP excluded by a geolocation rule.
- Missing the UTM parameter that activates a campaign variant.
- A custom predicate that reads a cookie set after SeaText initializes.
Local Storage and Cross-Origin Constraints
The script stores a visitor ID in localStorage. If your site runs in a sandboxed iframe, uses a restrictive CSP that blocks localStorage access, or serves the SeaText snippet from a different origin without proper CORS headers, the ID cannot be read or written. The script fails gracefully — no error, no functionality. Check the Application tab in DevTools: the key seatext_visitor_id should exist after the first page view.
Cross-origin issues also appear when the snippet is loaded from a CDN domain that doesn't send Access-Control-Allow-Origin headers matching your site. The script loads (browsers allow cross-origin script tags), but subsequent fetch calls to the SeaText API for variant payloads are blocked by CORS. These blocked requests appear in the Network tab with a red status, not in the Console.
Verification Checklist
| Check | How to Verify | Expected Result |
|---|---|---|
| Script loaded | Network tab → filter "seatext" | 200 OK, JavaScript MIME type |
| Global registered | Console: typeof SeaText | "object" |
| Init called | Console: SeaText.init.toString() | Function body visible |
| Config valid | Console: SeaText.config (after init) | Object with projectId |
| Target elements exist | Elements panel → search selector | At least one match |
| Targeting passes | Call SeaText.debug(true), reload | Console shows rule evaluation |
| Local storage writable | Application → Local Storage | seatext_visitor_id present |
| API reachable | Network tab → filter "api.seatext" | 200 on variant fetch |
Key Facts
| Property | Detail |
|---|---|
| Script loading | Async snippet, under 15 KB, executes before visual paint |
| Initialization | Requires explicit SeaText.init(config) call |
| SPA support | Snippet in index.html body; call SeaText.refresh() after route changes |
| Targeting | UTM, referrer, geo, cookies, custom predicates |
| Debug mode | SeaText.debug(true) logs targeting and rewrite decisions |
| Local storage | Stores seatext_visitor_id; requires same-origin access |
| CORS | API calls from snippet domain must allow your origin |
Limitations of This Diagnostic
This guide covers client-side silent failures only. It does not address server-side rendering mismatches, edge-worker rewrites, or SeaText dashboard configuration errors (e.g., unpublished variants, paused agents). If the checklist passes but features remain absent, the issue is likely in the SeaText project settings — variant status, agent activation, or traffic allocation — which require dashboard access to inspect.
Terminology
- Silent failure: Script loads and initializes without console errors, but no visible changes occur on the page.
- Targeting rule: A condition (UTM, referrer, geo, cookie, custom function) that determines whether a variant applies to the current visitor.
- Variant: An alternative version of a text element (headline, CTA, product description) that SeaText swaps in when targeting matches.
- Refresh: A manual call (
SeaText.refresh()) that triggers a new DOM scan and rewrite pass, needed after SPA route changes. - Visitor ID: A persistent identifier stored in
localStorageto maintain variant assignment across sessions.
FAQ
Why does SeaText work in production but not on my localhost?
Localhost often fails targeting rules that require a valid UTM parameter, a recognized referrer, or a geolocation that resolves to a supported country. Add a local-only targeting rule in the dashboard or use SeaText.debug(true) to see which rule blocks you.
Do I need to call SeaText.init() on every SPA route change?
No. Call init() once at app bootstrap. After each route change that mounts new translatable content, call SeaText.refresh().
Can a bundler (Webpack, Vite) break SeaText?
Yes. If the bundler renames the global SeaText variable or strips the async script tag during HTML processing, the queue mechanism fails. Keep the snippet in index.html outside the bundle, or use the npm package if available.
What does SeaText.debug(true) actually log?
It prints: targeting rule evaluation (rule name, visitor value, pass/fail), variant selection (variant ID, element selector, original text, new text), and any skipped rewrites with reason (element not found, already rewritten, CLS protection).
How do I know if CORS is blocking API calls?
Open the Network tab, filter for "seatext" or "api.seatext". Failed CORS requests show status "(blocked)" or 0 bytes transferred with a red warning icon. The Console may also show a CORS error message even when other scripts are silent.
Does SeaText work inside a sandboxed iframe?
Only if the iframe has allow-scripts and allow-same-origin (or the snippet origin matches the parent). Without allow-same-origin, localStorage is inaccessible and the visitor ID cannot persist.
What if the checklist passes but nothing changes?
Check the SeaText dashboard: ensure at least one agent (CRO, Translation, Ads, etc.) is active, variants are published, and traffic allocation is > 0%. The client script only executes decisions made in the dashboard.
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