		@@ -5,2 +5,4 @@ 'use strict';

		var constants = require('./constants.js');

		function fromInsideIframe({
		@@ -11,4 +13,10 @@ targetOrigin = '*'
		throw new Error(`This does not appear to be a child iframe, because there is no parent window.`);
		}
		} // We wait until the document is ready before advertising to the parent that
		// communication can commence.
		// However, it's possible that the parent isn't listening to messages at this time.
		// Which can lead to communication never starting.
		// Therefore we also wait for the parent to send a message once it's ready to (re)send the
		// ready message from within the child iframe.


		const {
		@@ -18,6 +26,14 @@ parent

		const ready = () => parent.postMessage('remote-ui::ready', targetOrigin); // Listening to `readyState` in iframe, though the child iframe could probably
		// send a `postMessage` that it is ready to receive messages sooner than that.
		const ready = () => parent.postMessage(constants.READY_MESSAGE_KEY, targetOrigin);

		window.addEventListener('message', event => {
		if (event.source !== parent \|\| document.readyState !== 'complete') {
		return;
		}

		if (event.data === constants.READY_MESSAGE_KEY) {
		ready();
		}
		});

		if (document.readyState === 'complete') {
		@@ -24,0 +40,0 @@ ready();

build/cjs/adaptors/iframe-parent.js

		@@ -5,2 +5,4 @@ 'use strict';

		var constants = require('./constants.js');

		function fromIframe(target, {
		@@ -10,2 +12,4 @@ terminate: shouldTerminate = true,
		} = {}) {
		var _target$contentWindow;

		if (typeof window === 'undefined') {
		@@ -24,3 +28,3 @@ throw new Error(`You can only run fromIframe() in a browser context, but no window was found.`);

		if (event.data === 'remote-ui::ready') {
		if (event.data === constants.READY_MESSAGE_KEY) {
		window.removeEventListener('message', onMessage);
		@@ -31,2 +35,3 @@ resolveIFrameReadyPromise();

		(_target$contentWindow = target.contentWindow) === null \|\| _target$contentWindow === void 0 ? void 0 : _target$contentWindow.postMessage(constants.READY_MESSAGE_KEY, targetOrigin);
		const iframeReadyPromise = new Promise(resolve => {
		@@ -33,0 +38,0 @@ resolveIFrameReadyPromise = resolve;

CHANGELOG.md

		# Changelog

		## 1.4.2

		### Patch Changes

		- [#215](https://github.com/Shopify/remote-ui/pull/215) [`981d67c`](https://github.com/Shopify/remote-ui/commit/981d67c60754dc6e9f5dbee5794dffcaeb902261) Thanks [@robin-drexler](https://github.com/robin-drexler)! - Ensures iframe connection can always be established

		## 1.4.1
		@@ -4,0 +10,0 @@

package.json

		{
		"name": "@remote-ui/rpc",
		"description": "An RPC library with strong support for simulating the transfer of functions via postMessage",
		"version": "1.4.1",
		"version": "1.4.2",
		"publishConfig": {
		@@ -6,0 +6,0 @@ "access": "public"

src/adaptors/iframe-child.ts

		import type {MessageEndpoint} from '../types';

		import {READY_MESSAGE_KEY} from './constants';

		export function fromInsideIframe({targetOrigin = '*'} = {}): MessageEndpoint {
		@@ -10,8 +12,25 @@ if (typeof self === 'undefined' \|\| self.parent == null) {

		// We wait until the document is ready before advertising to the parent that
		// communication can commence.

		// However, it's possible that the parent isn't listening to messages at this time.
		// Which can lead to communication never starting.

		// Therefore we also wait for the parent to send a message once it's ready to (re)send the
		// ready message from within the child iframe.

		const {parent} = self;

		const ready = () => parent.postMessage('remote-ui::ready', targetOrigin);
		const ready = () => parent.postMessage(READY_MESSAGE_KEY, targetOrigin);

		// Listening to `readyState` in iframe, though the child iframe could probably
		// send a `postMessage` that it is ready to receive messages sooner than that.
		window.addEventListener('message', (event) => {
		if (event.source !== parent \|\| document.readyState !== 'complete') {
		return;
		}

		if (event.data === READY_MESSAGE_KEY) {
		ready();
		}
		});

		if (document.readyState === 'complete') {
		@@ -18,0 +37,0 @@ ready();

src/adaptors/iframe-parent.ts

		import type {MessageEndpoint} from '../types';

		import {READY_MESSAGE_KEY} from './constants';

		export function fromIframe(
		@@ -26,3 +28,3 @@ target: HTMLIFrameElement,

		if (event.data === 'remote-ui::ready') {
		if (event.data === READY_MESSAGE_KEY) {
		window.removeEventListener('message', onMessage);
		@@ -33,2 +35,4 @@ resolveIFrameReadyPromise();

		target.contentWindow?.postMessage(READY_MESSAGE_KEY, targetOrigin);

		const iframeReadyPromise = new Promise<void>((resolve) => {
		@@ -42,3 +46,2 @@ resolveIFrameReadyPromise = resolve;
		await iframeReadyPromise;

		target.contentWindow!.postMessage(message, targetOrigin, transfer);
		@@ -45,0 +48,0 @@ },

build/esm/adaptors/iframe-child.mjs