const EXTERNAL_IMAGE_PLACEHOLDER = `data:image/svg+xml;charset=utf-8,${encodeURIComponent(` `)}`; const isExternalImageUrl = (value) => { if (!value) return false; const normalized = value.trim().toLowerCase(); return normalized.startsWith('http://') || normalized.startsWith('https://') || normalized.startsWith('//'); }; const srcsetHasExternalUrl = (value) => { if (!value) return false; return value.split(',').some((item) => isExternalImageUrl(item.trim().split(/\s+/)[0])); }; export const applyExternalImagePolicy = (html, autoLoadExternalImages) => { if (autoLoadExternalImages || !html) { return html || ''; } if (typeof DOMParser !== 'function') { return html; } const hasDocumentShell = /]/i.test(html); const doc = new DOMParser().parseFromString(html, 'text/html'); for (const image of doc.querySelectorAll('img')) { const src = image.getAttribute('src') || ''; const srcset = image.getAttribute('srcset') || ''; if (!isExternalImageUrl(src) && !srcsetHasExternalUrl(srcset)) { continue; } if (src) image.setAttribute('data-blocked-src', src); if (srcset) image.setAttribute('data-blocked-srcset', srcset); image.removeAttribute('srcset'); image.setAttribute('src', EXTERNAL_IMAGE_PLACEHOLDER); image.setAttribute('loading', 'lazy'); image.style.maxWidth = '100%'; image.style.height = 'auto'; image.style.border = '1px solid #d1d5db'; image.style.borderRadius = '8px'; } if (hasDocumentShell) { return `\n${doc.documentElement.outerHTML}`; } return doc.body.innerHTML; };