Frame Bridge

Seamless URL synchronization and communication for iframe-embedded applications.

The Problem

When you embed an application in an iframe (a search system, documentation site, store, etc.), the parent page URL becomes static. This breaks:

Deep linking - Users can't link to specific pages within the iframe
SEO - Search engines can't index individual pages in your embedded app
Bookmarking - Users can't bookmark specific states
Browser navigation - Back/forward buttons don't work as expected

The Solution

Frame Bridge automatically synchronizes URLs between parent and child frames, passes parameters bidirectionally, and handles iframe dimensions and messaging - making your embedded application behave like a native part of the parent site.

<!-- Parent URL: https://example.com/experts?term=biology -->
<!-- Iframe navigates to: /search/results -->
<!-- Parent URL updates to: https://example.com/experts?route=/search/results&term=biology -->

Users can now bookmark, share, and search engines can index every page in your embedded app.

Features

URL Synchronization - Keep parent URL in sync with iframe routes
Parameter Passing - Pass query parameters from parent to child
Automatic Resizing - ResizeObserver-based height updates
Promise-based Messaging - Clean async/await API for parent-child communication
JSON-LD Injection - SEO-friendly structured data from iframes
Origin Validation - Secure cross-origin communication
Multiple Iframes - Support for multiple child frames
Zero Config - Works out of the box with sensible defaults

Installation

Coming soon (not yet published to npm)

npm install @uniweb/frame-bridge

Or use via CDN:

<!-- Parent -->
<script src="https://cdn.jsdelivr.net/npm/@uniweb/frame-bridge@1.0.0/dist/auto/parent.min.js"></script>

<!-- Child -->
<script src="https://cdn.jsdelivr.net/npm/@uniweb/frame-bridge@1.0.0/dist/auto/child.min.js"></script>

Quick Start

Zero Config (Auto-init)

Parent HTML:

<!DOCTYPE html>
<html>
  <head>
    <script src="https://cdn.../parent.min.js"></script>
  </head>
  <body>
    <!-- Embed your application -->
    <iframe src="https://app.example.com" data-messenger-id="main"></iframe>

    <script>
      // URLs are automatically synchronized
      window.FrameBridge.on("routeChange", (id, { path, title }) => {
        console.log("Iframe navigated to:", path);
        // Parent URL automatically updated to: ?route=/new-path
      });
    </script>
  </body>
</html>

Child HTML (in iframe):

<!DOCTYPE html>
<html>
  <head>
    <script src="https://cdn.../child.min.js"></script>
  </head>
  <body>
    <h1>My Embedded Application</h1>

    <script>
      // Access parameters passed from parent URL
      window.FrameBridge.on("parentReady", ({ params }) => {
        console.log("Received params:", params);
        // If parent URL is: ?term=biology&filter=active
        // params = { term: 'biology', filter: 'active' }
      });

      // Navigate and parent URL updates automatically
      window.location.href = "/search/results";
    </script>
  </body>
</html>

That's it! URLs are synchronized, parameters are passed, and the iframe resizes automatically.

NPM Usage with Custom Configuration

Parent Setup

import { ParentMessenger } from "@uniweb/frame-bridge/parent";

const messenger = new ParentMessenger({
  // Security
  allowedOrigins: ["https://app.example.com"],

  // URL sync config (all default to true)
  urlSync: true,
  urlParamKey: "route", // ?route=/users/123
  preserveOtherParams: true, // Keep other query params

  // Pass config to children
  analyticsId: "GA-XXXXX",
  syncParams: ["term", "filter"], // Only sync these params to iframe

  // Features
  autoResize: true, // Automatically resize iframe to content
  jsonLD: true, // Inject JSON-LD from iframe into parent

  // Callbacks
  onIframeReady: (id, { route, dimensions }) => {
    console.log(`Iframe ready at ${route.path}`);
  },

  onRouteChange: (id, { path, title }) => {
    console.log(`Iframe navigated to ${path}`);
    // Parent URL automatically updated
  },

  onDimensionUpdate: (id, { height }) => {
    console.log(`Iframe height: ${height}px`);
    // Iframe automatically resized
  },
});

// Programmatic control
messenger.sendToChild("iframe-id", "navigate", { path: "/users/123" });
messenger.sendToAllChildren("setTheme", { theme: "dark" });

Child Setup

import { ChildMessenger } from "@uniweb/frame-bridge/child";

const messenger = new ChildMessenger({
  // Security
  allowedOrigins: ["https://parent.example.com"],

  // Features
  dimensionReporting: true,
  routeReporting: true,

  // Custom route getter (for SPAs)
  getRoute: () => ({
    path: window.location.pathname,
    title: document.title,
  }),

  // Callbacks
  onParentReady: ({ params, config }) => {
    console.log("Received params:", params);
    console.log("Analytics ID:", config.analyticsId);

    // Use params to initialize your app
    if (params.term) {
      performSearch(params.term);
    }
  },

  onNavigate: ({ path }) => {
    // Parent requested navigation
    window.history.pushState({}, "", path);
  },

  onParamUpdate: (params) => {
    // Parent URL params changed
    console.log("Updated params:", params);
  },
});

// Update route manually (e.g., after navigation)
messenger.updateRoute("/search/results", "Search Results");

// Update JSON-LD for SEO
messenger.updateJSONLD({
  "@context": "https://schema.org",
  "@type": "SearchResultsPage",
  name: "Expert Search Results",
});

// Get current params
const searchTerm = messenger.getParam("term");
const allParams = messenger.getAllParams();

React Integration

Child with React Router:

import { useEffect } from "react";
import { useLocation, useSearchParams } from "react-router-dom";
import { ChildMessenger } from "@uniweb/frame-bridge/child";

const messenger = new ChildMessenger({
  getRoute: () => ({
    path: window.location.pathname,
    title: document.title,
  }),
  onParentReady: ({ params }) => {
    // Initialize app with params from parent URL
    console.log("Parent params:", params);
  },
  onNavigate: ({ path }) => {
    window.history.pushState({}, "", path);
  },
});

// Hook to report route changes
export function useRouteReporter() {
  const location = useLocation();

  useEffect(() => {
    messenger.updateRoute(location.pathname, document.title);
  }, [location]);
}

// In your App component
function App() {
  useRouteReporter();
  return <Routes>{/* Your routes */}</Routes>;
}

Parent with React:

import { useEffect, useState } from "react";
import { ParentMessenger } from "@uniweb/frame-bridge/parent";

function EmbeddedApp() {
  const [iframeRoute, setIframeRoute] = useState("/");
  const [messenger] = useState(
    () =>
      new ParentMessenger({
        onRouteChange: (id, { path }) => {
          setIframeRoute(path);
        },
      })
  );

  useEffect(() => {
    return () => messenger.destroy();
  }, [messenger]);

  return (
    <div>
      <iframe src="https://app.example.com" />
    </div>
  );
}

Use Cases

Embedded Search System

Parent URL: example.com/experts?term=biology
→ Iframe searches and shows results
→ User clicks an expert
→ Parent URL updates to: example.com/experts?route=/profile/john-doe&term=biology
→ URL is bookmarkable and indexable

Embedded Documentation

Parent URL: example.com/docs
→ User navigates through docs
→ Parent URL updates to: example.com/docs?route=/guides/getting-started
→ Deep links work, search engines index individual pages

Embedded Store

Parent URL: example.com/shop
→ User browses categories and products
→ Parent URL updates to: example.com/shop?route=/products/widget-123
→ Products are individually linkable and indexable

Advanced Features

Accurate Dimension Reporting

The library automatically accounts for body margin, padding, and border:

// Child automatically includes all body spacing
const dimensions = {
  width: 1200,
  height: 1840, // = content (1800px) + margin (20px) + padding (20px)
};

Custom Actions

Define bidirectional custom actions:

// Parent
const messenger = new ParentMessenger({
  actionHandlers: {
    userSelected: (iframeId, { userId }) => {
      console.log(`User ${userId} selected`);
      return { success: true };
    },
  },
});

// Child
const messenger = new ChildMessenger({
  actionHandlers: {
    loadUser: ({ userId }) => {
      return { user: { id: userId, name: "John" } };
    },
  },
});

// Usage with promises
const result = await messenger.sendToParent("userSelected", { userId: 123 });

Multiple Iframes

const messenger = new ParentMessenger({
  onIframeReady: (id, info) => {
    console.log("Iframe registered:", id);
  },
});

// Send to specific iframe
messenger.sendToChild("iframe-1", "action", { data: "value" });

// Send to all iframes
messenger.sendToAllChildren("action", { data: "value" });

// Get iframe info
const iframe = messenger.getIframe("iframe-1");
const allIframes = messenger.getAllIframes();

JSON-LD for SEO

// Child sends structured data
messenger.updateJSONLD({
  "@context": "https://schema.org",
  "@type": "Product",
  name: "Widget",
  offers: {
    "@type": "Offer",
    price: "19.99",
  },
});

// Parent automatically injects into <head>

Security

// Parent: Only accept messages from specific origins
const messenger = new ParentMessenger({
  allowedOrigins: [
    "https://app.example.com",
    "https://*.trusted.com", // Wildcard support
  ],
});

// Child: Only accept messages from parent origin
const messenger = new ChildMessenger({
  allowedOrigins: ["https://parent.example.com"],
});

API Reference

ParentMessenger

Constructor Options

Option	Type	Default	Description
`allowedOrigins`	`string[]`	Same-origin only	Allowed child origins
`urlSync`	`boolean`	`true`	Sync URL with iframe routes
`urlParamKey`	`string`	`'path'`	Query param key for routes
`preserveOtherParams`	`boolean`	`true`	Keep other query params
`autoResize`	`boolean`	`true`	Auto-resize iframes
`jsonLD`	`boolean`	`true`	Enable JSON-LD injection
`analyticsId`	`string`	-	GA ID to pass to children
`syncParams`	`string[]`	All params	Params to sync to iframe
`onIframeReady`	`function`	-	Iframe ready callback
`onRouteChange`	`function`	-	Route change callback
`onDimensionUpdate`	`function`	-	Dimension update callback
`actionHandlers`	`object`	-	Custom action handlers
`timeout`	`number`	`5000`	Message timeout (ms)
`logLevel`	`string\|number`	`'info'`	Logging level

Methods

sendToChild(iframeId, action, params) - Send message to specific iframe
sendToAllChildren(action, params) - Send message to all iframes
getIframe(iframeId) - Get iframe metadata
getAllIframes() - Get all iframe metadata
setLogLevel(level) - Change log level
destroy() - Cleanup and destroy

ChildMessenger

Constructor Options

Option	Type	Default	Description
`allowedOrigins`	`string[]`	Same-origin only	Allowed parent origins
`dimensionReporting`	`boolean`	`true`	Enable dimension reporting
`dimensionThreshold`	`number`	`1`	Min px change to report
`routeReporting`	`boolean`	`true`	Enable route reporting
`getRoute`	`function`	-	Custom route getter
`onParentReady`	`function`	-	Parent ready callback
`onNavigate`	`function`	-	Navigation request callback
`onParamUpdate`	`function`	-	Param update callback
`actionHandlers`	`object`	-	Custom action handlers
`metadata`	`object`	-	Metadata to send with announce
`timeout`	`number`	`5000`	Message timeout (ms)
`logLevel`	`string\|number`	`'info'`	Logging level

Methods

sendToParent(action, params) - Send message to parent
updateRoute(path, title) - Manually update route
updateDimensions() - Manually trigger dimension update
updateJSONLD(jsonld) - Update JSON-LD structured data
getParam(key) - Get parameter value
getAllParams() - Get all parameters
getConfig(key) - Get config value
setLogLevel(level) - Change log level
destroy() - Cleanup and destroy

Browser Support

Modern browsers with ES6+ support
ResizeObserver (with fallback for older browsers)
postMessage API

License

Contributing

Contributions are welcome! Please open an issue or PR.

Name		Name	Last commit message	Last commit date
Latest commit History 14 Commits
demos		demos
src		src
tests		tests
.gitignore		.gitignore
.prettierrc		.prettierrc
CHANGELOG.md		CHANGELOG.md
CLAUDE.md		CLAUDE.md
GETTING_STARTED.md		GETTING_STARTED.md
IMPLEMENTATION_CHECKLIST.md		IMPLEMENTATION_CHECKLIST.md
LICENSE		LICENSE
PROJECT_SUMMARY.md		PROJECT_SUMMARY.md
README.md		README.md
package-lock.json		package-lock.json
package.json		package.json
rollup.config.js		rollup.config.js
vitest.config.js		vitest.config.js

License

uniweb/frame-bridge

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Frame Bridge

The Problem

The Solution

Features

Installation

Quick Start

Zero Config (Auto-init)

NPM Usage with Custom Configuration

Parent Setup

Child Setup

React Integration

Use Cases

Embedded Search System

Embedded Documentation

Embedded Store

Advanced Features

Accurate Dimension Reporting

Custom Actions

Multiple Iframes

JSON-LD for SEO

Security

API Reference

ParentMessenger

Constructor Options

Methods

ChildMessenger

Constructor Options

Methods

Browser Support

License

Contributing

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