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Editor iframe: memoize src blob URL to prevent unwanted revokes #75619

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Merged
jsnajdr merged 1 commit into from
Feb 18, 2026
Merged

Editor iframe: memoize src blob URL to prevent unwanted revokes #75619

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102 changes: 51 additions & 51 deletions packages/block-editor/src/components/iframe/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,13 +6,7 @@ import clsx from 'clsx';
/**
* WordPress dependencies
*/
import {
useState,
createPortal,
forwardRef,
useMemo,
useEffect,
} from '@wordpress/element';
import { useState, createPortal, forwardRef } from '@wordpress/element';
import { __ } from '@wordpress/i18n';
import {
useMergeRefs,
Expand Down Expand Up @@ -102,6 +96,54 @@ function useBubbleEvents( iframeDocument ) {
} );
}

const iframeSrcCache = new WeakMap();
const iframeSrcCleanup = globalThis.FinalizationRegistry
? new globalThis.FinalizationRegistry( ( url ) =>
URL.revokeObjectURL( url )
)
: undefined;

function getIframeSrc( resolvedAssets ) {
let src = iframeSrcCache.get( resolvedAssets );
if ( src ) {
return src;
}

// Correct doctype is required to enable rendering in standards mode.
// Also preload the styles to avoid a flash of unstyled content.
const html = `<!doctype html>
<html>
<head>
<meta charset="utf-8">
<base href="${ window.location.href }">
<script>window.frameElement._load()</script>
<style>
html{
height: auto !important;
min-height: 100%;
}
/* Lowest specificity to not override global styles */
:where(body) {
margin: 0;
/* Default background color in case zoom out mode background
colors the html element */
background-color: white;
}
</style>
${ resolvedAssets.styles ?? '' }
${ resolvedAssets.scripts ?? '' }
</head>
<body>
<script>document.currentScript.parentElement.remove()</script>
</body>
</html>`;

src = URL.createObjectURL( new Blob( [ html ], { type: 'text/html' } ) );
iframeSrcCache.set( resolvedAssets, src );
iframeSrcCleanup?.register( resolvedAssets, src );
return src;
}

function Iframe( {
contentRef,
children,
Expand All @@ -114,14 +156,12 @@ function Iframe( {
...props
} ) {
const { resolvedAssets, isPreviewMode } = useSelect( ( select ) => {
const { getSettings } = select( blockEditorStore );
const settings = getSettings();
const settings = select( blockEditorStore ).getSettings();
return {
resolvedAssets: settings.__unstableResolvedAssets,
isPreviewMode: settings.isPreviewMode,
};
}, [] );
const { styles = '', scripts = '' } = resolvedAssets;
/** @type {[Document, React.Dispatch<Document>]} */
const [ iframeDocument, setIframeDocument ] = useState();
const [ bodyClasses, setBodyClasses ] = useState( [] );
Expand Down Expand Up @@ -251,44 +291,7 @@ function Iframe( {
disabledRef,
] );

// Correct doctype is required to enable rendering in standards
// mode. Also preload the styles to avoid a flash of unstyled
// content.
const html = `<!doctype html>
<html>
<head>
<meta charset="utf-8">
<base href="${ window.location.origin }">
<script>window.frameElement._load()</script>
<style>
html{
height: auto !important;
min-height: 100%;
}
/* Lowest specificity to not override global styles */
:where(body) {
margin: 0;
/* Default background color in case zoom out mode background
colors the html element */
background-color: white;
}
</style>
${ styles }
${ scripts }
</head>
<body>
<script>document.currentScript.parentElement.remove()</script>
</body>
</html>`;

const [ src, cleanup ] = useMemo( () => {
const _src = URL.createObjectURL(
new window.Blob( [ html ], { type: 'text/html' } )
);
return [ _src, () => URL.revokeObjectURL( _src ) ];
}, [ html ] );

useEffect( () => cleanup, [ cleanup ] );
const src = getIframeSrc( resolvedAssets );

// Make sure to not render the before and after focusable div elements in view
// mode. They're only needed to capture focus in edit mode.
Expand All @@ -307,9 +310,6 @@ function Iframe( {
} }
ref={ useMergeRefs( [ ref, setRef ] ) }
tabIndex={ tabIndex }
// Correct doctype is required to enable rendering in standards
// mode. Also preload the styles to avoid a flash of unstyled
// content.
src={ src }
title={ title }
onKeyDown={ ( event ) => {
Expand Down
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