theseus/bundled-addons/docx-editor/lib/pkg.js

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feat(docx-editor): edit Word documents without quietly eating what Word put in them A .docx editor is easy to write badly: read the file into HTML, let someone edit it, write a fresh document back, and hand them a file that lost its headers, its page size and half its formatting without ever saying so. Three things keep this one honest. The reader doesn't use mammoth's HTML. mammoth's converter is deliberately semantic, and HTML has nowhere to put a run's colour or a paragraph's line spacing, so it drops them — and those are controls this editor puts in the ribbon. Taking its parsed document model instead means what the ribbon offers is what the file can actually carry. Six properties mammoth's model didn't keep are added by build-time patches, each asserting its anchor so an upgrade that moves the code fails the build rather than shipping a lossy reader. The writer rebuilds the body but carries the rest of the package across: headers, footers, footnotes, endnotes, the document's own style catalogue, its theme and its page setup, with relationship ids and content types re-wired. Word features the editor can't model are still lost, so they are detected when the file opens and named in a banner before anyone edits. Tracked changes get their own gate. mammoth renders insertions as ordinary text and drops deletions, so saving would accept every pending revision without Word ever asking. Such a document opens read-only until the user says that is what they want. Verified over 66 real documents: 65 round-trip with an identical model and a structurally valid package, the one exception being a 7 MB WMF picture, which no browser can display and the writer cannot emit. Also driven end to end through a real Theseus over CDP — sidebar, ribbon, typing, save, reopen.
2026-09-20 20:46:29 +02:00
// Package-level work on a .docx: everything that happens at the zip layer,
// either side of mammoth and the docx builder.
//
// Two jobs:
//
// scan(zip) — walk the original package and report what's in it that the
// v1 editor can't render, so the user is told BEFORE they
// edit rather than after they've lost something.
//
// graft(...) — the save-side half of the preservation deal. docx (the npm
// builder) always emits a brand-new package, so anything that
// lives outside the document body would vanish on save. We
// take the parts that survive a body rewrite unharmed —
// headers, footers, footnotes, endnotes, the style catalogue,
// the theme, page setup — and carry them across from the
// original into the freshly built package, re-wiring
// relationship ids and content types as we go.
//
// Body-level things we can't model (textboxes, shapes, equations, content
// controls, fields) are NOT preserved; scan() names them so the loss is
// visible. See ROUND-TRIP.md for the full ledger.
(function (root, factory) {
const api = factory();
if (typeof module === "object" && module.exports) module.exports = api;
root.DocxEditor = Object.assign(root.DocxEditor || {}, { pkg: api });
})(typeof globalThis !== "undefined" ? globalThis : this, function () {
"use strict";
const V = () => globalThis.DOCXV;
const W_NS = "http://schemas.openxmlformats.org/wordprocessingml/2006/main";
const R_NS = "http://schemas.openxmlformats.org/officeDocument/2006/relationships";
const CT_NS = "http://schemas.openxmlformats.org/package/2006/content-types";
const PR_NS = "http://schemas.openxmlformats.org/package/2006/relationships";
const CONTENT_TYPES = {
header: "application/vnd.openxmlformats-officedocument.wordprocessingml.header+xml",
footer: "application/vnd.openxmlformats-officedocument.wordprocessingml.footer+xml",
footnotes: "application/vnd.openxmlformats-officedocument.wordprocessingml.footnotes+xml",
endnotes: "application/vnd.openxmlformats-officedocument.wordprocessingml.endnotes+xml",
};
const REL_TYPES = {
header: R_NS + "/header",
footer: R_NS + "/footer",
footnotes: R_NS + "/footnotes",
endnotes: R_NS + "/endnotes",
image: R_NS + "/image",
};
function parseXml(text) {
const doc = new DOMParser().parseFromString(text, "application/xml");
const err = doc.getElementsByTagName("parsererror")[0];
if (err) throw new Error("malformed XML in package: " + err.textContent.slice(0, 200));
return doc;
}
function serializeXml(doc) {
const body = new XMLSerializer().serializeToString(doc);
return body.startsWith("<?xml")
? body
: '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>\r\n' + body;
}
// Namespace-agnostic child lookup: packages in the wild are inconsistent
// about prefixes, and getElementsByTagNameNS is the only reliable route.
function kids(el, ns, local) {
return Array.prototype.filter.call(el.childNodes,
(n) => n.nodeType === 1 && n.namespaceURI === ns && n.localName === local);
}
function firstKid(el, ns, local) { return kids(el, ns, local)[0] || null; }
function descendants(doc, ns, local) {
return Array.prototype.slice.call(doc.getElementsByTagNameNS(ns, local));
}
async function loadZip(bytes) {
return V().JSZip.loadAsync(bytes);
}
async function textOf(zip, path) {
const f = zip.file(path);
return f ? f.async("string") : null;
}
// ---------------------------------------------------------------- scan ---
// What the scan can say about a feature.
// preserved — survives a save untouched (carried across by graft()).
// lossy — the content survives but not exactly as Word wrote it.
// dropped — gone on save; the user needs to know before editing.
// blocked — dangerous to flatten silently; editing is gated on consent.
const FEATURES = [
{ key: "trackedChanges", level: "blocked", label: "Tracked changes",
note: "Saving would silently accept every pending revision.",
test: (d) => descendants(d, W_NS, "ins").length + descendants(d, W_NS, "del").length > 0 },
{ key: "comments", level: "blocked", label: "Comments",
note: "Comment anchors and the comment text are not carried across.",
test: (d, z) => !!z.file("word/comments.xml") &&
descendants(d, W_NS, "commentRangeStart").length > 0 },
{ key: "headers", level: "preserved", label: "Headers",
test: (d, z) => z.file(/^word\/header\d*\.xml$/).length > 0 },
{ key: "footers", level: "preserved", label: "Footers",
test: (d, z) => z.file(/^word\/footer\d*\.xml$/).length > 0 },
{ key: "footnotes", level: "preserved", label: "Footnotes",
test: (d, z) => !!z.file("word/footnotes.xml") &&
descendants(d, W_NS, "footnoteReference").length > 0 },
{ key: "endnotes", level: "preserved", label: "Endnotes",
test: (d, z) => !!z.file("word/endnotes.xml") &&
descendants(d, W_NS, "endnoteReference").length > 0 },
{ key: "pageSetup", level: "preserved", label: "Page size and margins",
test: (d) => descendants(d, W_NS, "sectPr").length > 0 },
{ key: "equations", level: "dropped", label: "Equations",
note: "OMML equations are removed from the body.",
test: (d) => d.getElementsByTagNameNS("http://schemas.openxmlformats.org/officeDocument/2006/math", "oMath").length > 0 },
{ key: "shapes", level: "dropped", label: "Shapes, text boxes and WordArt",
test: (d) => descendants(d, W_NS, "pict").length > 0 ||
d.getElementsByTagNameNS("http://schemas.openxmlformats.org/markup-compatibility/2006", "AlternateContent").length > 0 },
{ key: "contentControls", level: "dropped", label: "Content controls",
test: (d) => descendants(d, W_NS, "sdt").length > 0 },
{ key: "fields", level: "dropped", label: "Fields (page numbers, tables of contents, cross-references)",
note: "Field codes are dropped; the text Word last calculated is kept.",
test: (d) => descendants(d, W_NS, "fldSimple").length > 0 ||
descendants(d, W_NS, "instrText").length > 0 },
{ key: "bookmarks", level: "dropped", label: "Bookmarks",
test: (d) => descendants(d, W_NS, "bookmarkStart")
.some((b) => !(b.getAttributeNS(W_NS, "name") || "").startsWith("_GoBack") ) },
{ key: "sections", level: "dropped", label: "Multiple sections",
note: "Only the first section's page setup is kept; section breaks are lost.",
test: (d) => descendants(d, W_NS, "sectPr").length > 1 },
{ key: "columns", level: "dropped", label: "Multi-column layout",
test: (d) => descendants(d, W_NS, "cols").some((c) => {
const n = c.getAttributeNS(W_NS, "num");
return n && parseInt(n, 10) > 1;
}) },
{ key: "metafiles", level: "dropped", label: "Metafile pictures (WMF/EMF)",
note: "Word's vector picture format. Browsers can't display it and it can't be written back, so those pictures are lost on save.",
test: (d, z) => z.file(/^word\/media\/.*\.(wmf|emf)$/i).length > 0 },
{ key: "paragraphBorders", level: "lossy", label: "Paragraph borders and shading",
note: "A rule under an empty paragraph is kept as a horizontal rule; other borders are dropped.",
test: (d) => descendants(d, W_NS, "pBdr").length > 0 || descendants(d, W_NS, "shd").length > 0 },
{ key: "tabStops", level: "lossy", label: "Custom tab stops",
note: "Tab characters are kept, custom stop positions are not.",
test: (d) => descendants(d, W_NS, "tabs").length > 0 },
];
async function scan(zip) {
const xml = await textOf(zip, "word/document.xml");
if (!xml) throw new Error("not a Word document: word/document.xml is missing");
const doc = parseXml(xml);
const found = [];
for (const f of FEATURES) {
let hit = false;
try { hit = !!f.test(doc, zip); } catch { hit = false; }
if (hit) found.push({ key: f.key, level: f.level, label: f.label, note: f.note || "" });
}
return {
features: found,
blocked: found.filter((f) => f.level === "blocked"),
dropped: found.filter((f) => f.level === "dropped"),
lossy: found.filter((f) => f.level === "lossy"),
preserved: found.filter((f) => f.level === "preserved"),
};
}
// ------------------------------------------------------------ page setup ---
// The first sectPr, mapped onto what the docx builder wants. Word writes
// these in twips; the builder takes twips too, so this is mostly a rename.
async function readSectionSetup(zip) {
const xml = await textOf(zip, "word/document.xml");
if (!xml) return null;
const doc = parseXml(xml);
const sect = descendants(doc, W_NS, "sectPr")[0];
if (!sect) return null;
const num = (el, attr) => {
if (!el) return null;
const v = el.getAttributeNS(W_NS, attr);
return /^-?\d+$/.test(v || "") ? parseInt(v, 10) : null;
};
const pgSz = firstKid(sect, W_NS, "pgSz");
const pgMar = firstKid(sect, W_NS, "pgMar");
const setup = { page: {} };
if (pgSz) {
const w = num(pgSz, "w"), h = num(pgSz, "h");
const orient = pgSz.getAttributeNS(W_NS, "orient");
if (w && h) setup.page.size = { width: w, height: h, orientation: orient === "landscape" ? "landscape" : "portrait" };
}
if (pgMar) {
const m = {};
for (const [k, a] of [["top", "top"], ["right", "right"], ["bottom", "bottom"],
["left", "left"], ["header", "header"], ["footer", "footer"], ["gutter", "gutter"]]) {
const v = num(pgMar, a);
if (v !== null) m[k] = v;
}
if (Object.keys(m).length) setup.page.margin = m;
}
setup.titlePg = !!firstKid(sect, W_NS, "titlePg");
// Which header/footer parts this section points at, by type.
setup.refs = [];
for (const kind of ["header", "footer"]) {
for (const ref of kids(sect, W_NS, kind + "Reference")) {
setup.refs.push({
kind,
type: ref.getAttributeNS(W_NS, "type") || "default",
rId: ref.getAttributeNS(R_NS, "id") || "",
});
}
}
return setup;
}
// docProps/core.xml — cheap to carry, and losing the author of a document
// is the kind of small betrayal people notice.
async function readCoreProps(zip) {
const xml = await textOf(zip, "docProps/core.xml");
if (!xml) return {};
let doc; try { doc = parseXml(xml); } catch { return {}; }
const pick = (ns, local) => {
const el = doc.getElementsByTagNameNS(ns, local)[0];
return el && el.textContent ? el.textContent : undefined;
};
const DC = "http://purl.org/dc/elements/1.1/";
const CP = "http://schemas.openxmlformats.org/package/2006/metadata/core-properties";
return {
title: pick(DC, "title"),
creator: pick(DC, "creator"),
description: pick(DC, "description"),
subject: pick(DC, "subject"),
keywords: pick(CP, "keywords"),
lastModifiedBy: pick(CP, "lastModifiedBy"),
};
}
// --------------------------------------------------------------- graft ---
function relsPathFor(partPath) {
const i = partPath.lastIndexOf("/");
return partPath.slice(0, i) + "/_rels" + partPath.slice(i) + ".rels";
}
function nextRelId(relsDoc) {
let max = 0;
for (const r of descendants(relsDoc, PR_NS, "Relationship")) {
const m = /^rId(\d+)$/.exec(r.getAttribute("Id") || "");
if (m) max = Math.max(max, parseInt(m[1], 10));
}
return (n) => "rId" + (max + n);
}
function addRelationship(relsDoc, id, type, target) {
const el = relsDoc.createElementNS(PR_NS, "Relationship");
el.setAttribute("Id", id);
el.setAttribute("Type", type);
el.setAttribute("Target", target);
relsDoc.documentElement.appendChild(el);
}
function addOverride(ctDoc, partName, contentType) {
const already = descendants(ctDoc, CT_NS, "Override")
.some((o) => o.getAttribute("PartName") === partName);
if (already) return;
const el = ctDoc.createElementNS(CT_NS, "Override");
el.setAttribute("PartName", partName);
el.setAttribute("ContentType", contentType);
ctDoc.documentElement.appendChild(el);
}
function addDefaultExt(ctDoc, ext, contentType) {
const already = descendants(ctDoc, CT_NS, "Default")
.some((o) => (o.getAttribute("Extension") || "").toLowerCase() === ext.toLowerCase());
if (already) return;
const el = ctDoc.createElementNS(CT_NS, "Default");
el.setAttribute("Extension", ext);
el.setAttribute("ContentType", contentType);
ctDoc.documentElement.insertBefore(el, ctDoc.documentElement.firstChild);
}
// Copy one part plus anything its own .rels file points at. Media gets a
// fresh name whenever the generated package already has a file there, and
// the part's rels are rewritten to match — otherwise a header's logo would
// quietly replace an image from the body.
async function copyPartWithRels(orig, gen, partPath, usedMedia) {
const data = await orig.file(partPath).async("uint8array");
gen.file(partPath, data);
const rp = relsPathFor(partPath);
const relsText = await textOf(orig, rp);
if (!relsText) return;
const relsDoc = parseXml(relsText);
for (const rel of descendants(relsDoc, PR_NS, "Relationship")) {
if (rel.getAttribute("TargetMode") === "External") continue;
const target = rel.getAttribute("Target") || "";
// Targets in word/_rels/*.rels are relative to word/.
const src = ("word/" + target.replace(/^\.\//, "")).replace(/\/+/g, "/");
const f = orig.file(src);
if (!f) continue;
let dest = src;
if (gen.file(dest) && !usedMedia.has(src)) {
const dot = src.lastIndexOf(".");
dest = src.slice(0, dot) + "-carried" + usedMedia.size + src.slice(dot);
rel.setAttribute("Target", dest.replace(/^word\//, ""));
}
usedMedia.set(src, dest);
gen.file(dest, await f.async("uint8array"));
}
gen.file(rp, serializeXml(relsDoc));
}
// Merge the original style catalogue into the generated one. Where both
// define a style id, the ORIGINAL wins: it is what the document actually
// looked like, and the builder's defaults are only there to make a blank
// document presentable. Styles the original doesn't have (the editor's own
// SourceCode, for instance) are left in place.
async function mergeStyles(orig, gen) {
const origText = await textOf(orig, "word/styles.xml");
const genText = await textOf(gen, "word/styles.xml");
if (!origText || !genText) return { merged: 0 };
const origDoc = parseXml(origText);
const genDoc = parseXml(genText);
const genRoot = genDoc.documentElement;
const byId = new Map();
for (const s of kids(genRoot, W_NS, "style")) {
byId.set(s.getAttributeNS(W_NS, "styleId"), s);
}
let merged = 0;
for (const s of descendants(origDoc, W_NS, "style")) {
const id = s.getAttributeNS(W_NS, "styleId");
if (!id) continue;
const imported = genDoc.importNode(s, true);
const existing = byId.get(id);
if (existing) genRoot.replaceChild(imported, existing);
else genRoot.appendChild(imported);
byId.set(id, imported);
merged++;
}
// docDefaults carries the document's base font and spacing; without it a
// grafted style catalogue sits on the builder's defaults and every
// unstyled paragraph shifts.
const origDefaults = descendants(origDoc, W_NS, "docDefaults")[0];
if (origDefaults) {
const genDefaults = kids(genRoot, W_NS, "docDefaults")[0];
const imported = genDoc.importNode(origDefaults, true);
if (genDefaults) genRoot.replaceChild(imported, genDefaults);
else genRoot.insertBefore(imported, genRoot.firstChild);
}
gen.file("word/styles.xml", serializeXml(genDoc));
return { merged };
}
// Header/footer references have to be the FIRST children of sectPr — the
// schema is order-sensitive and Word refuses a file that gets it wrong.
function injectSectionRefs(docDoc, refs, titlePg) {
const sect = descendants(docDoc, W_NS, "sectPr")[0];
if (!sect) return 0;
let n = 0;
const anchor = sect.firstChild;
for (const ref of refs) {
const el = docDoc.createElementNS(W_NS, "w:" + ref.kind + "Reference");
el.setAttributeNS(W_NS, "w:type", ref.type);
el.setAttributeNS(R_NS, "r:id", ref.newRId);
sect.insertBefore(el, anchor);
n++;
}
if (titlePg && !firstKid(sect, W_NS, "titlePg")) {
// titlePg sits after the references but before pgSz; appending is fine
// because Word tolerates it at the tail of sectPr in practice, and the
// references above are the order-critical part.
sect.appendChild(docDoc.createElementNS(W_NS, "w:titlePg"));
}
return n;
}
/**
* Carry preserved parts from the original package into the generated one.
*
* @param {Uint8Array} originalBytes the .docx the user opened
* @param {Uint8Array} generatedBytes what the docx builder just produced
* @param {object} opts { headers, footers, notes, styles, theme }
* @returns {Promise<{bytes: Uint8Array, carried: string[]}>}
*/
async function graft(originalBytes, generatedBytes, opts) {
const o = Object.assign({ headers: true, footers: true, notes: true, styles: true, theme: true }, opts || {});
const orig = await loadZip(originalBytes);
const gen = await loadZip(generatedBytes);
const carried = [];
const ctText = await textOf(gen, "[Content_Types].xml");
const ctDoc = parseXml(ctText);
const relsText = await textOf(gen, "word/_rels/document.xml.rels");
const relsDoc = parseXml(relsText);
const mkId = nextRelId(relsDoc);
let idN = 0;
const usedMedia = new Map();
// --- headers and footers -------------------------------------------
const setup = await readSectionSetup(orig);
const origRels = await textOf(orig, "word/_rels/document.xml.rels");
const origRelsDoc = origRels ? parseXml(origRels) : null;
const targetOf = (rId) => {
if (!origRelsDoc) return null;
const hit = descendants(origRelsDoc, PR_NS, "Relationship")
.find((r) => r.getAttribute("Id") === rId);
return hit ? "word/" + (hit.getAttribute("Target") || "").replace(/^\.\//, "") : null;
};
const newRefs = [];
if (setup && setup.refs.length) {
for (const ref of setup.refs) {
if (ref.kind === "header" && !o.headers) continue;
if (ref.kind === "footer" && !o.footers) continue;
const part = targetOf(ref.rId);
if (!part || !orig.file(part)) continue;
await copyPartWithRels(orig, gen, part, usedMedia);
const newRId = mkId(++idN);
addRelationship(relsDoc, newRId, REL_TYPES[ref.kind], part.replace(/^word\//, ""));
addOverride(ctDoc, "/" + part, CONTENT_TYPES[ref.kind]);
newRefs.push({ kind: ref.kind, type: ref.type, newRId });
}
if (newRefs.length) carried.push(`${newRefs.length} header/footer part(s)`);
}
// --- footnotes and endnotes -----------------------------------------
// The body keeps its footnote references (see read.js), so the note text
// has to come across with the same ids the references use — which is
// exactly what copying the original part wholesale gives us. The builder
// writes its own footnotes.xml only when the document declares notes, so
// in practice this replaces an absent or separator-only part.
if (o.notes) {
for (const kind of ["footnotes", "endnotes"]) {
const part = `word/${kind}.xml`;
if (!orig.file(part)) continue;
await copyPartWithRels(orig, gen, part, usedMedia);
addOverride(ctDoc, "/" + part, CONTENT_TYPES[kind]);
const has = descendants(relsDoc, PR_NS, "Relationship")
.some((r) => r.getAttribute("Type") === REL_TYPES[kind]);
if (!has) addRelationship(relsDoc, mkId(++idN), REL_TYPES[kind], `${kind}.xml`);
carried.push(kind);
}
}
// --- styles and theme ------------------------------------------------
if (o.styles) {
const r = await mergeStyles(orig, gen);
if (r.merged) carried.push(`${r.merged} style definition(s)`);
}
if (o.theme) {
const themeFile = orig.file(/^word\/theme\/theme\d*\.xml$/)[0];
if (themeFile) {
const genTheme = gen.file(/^word\/theme\/theme\d*\.xml$/)[0];
const dest = genTheme ? genTheme.name : "word/theme/theme1.xml";
gen.file(dest, await themeFile.async("uint8array"));
if (!genTheme) {
addOverride(ctDoc, "/" + dest, "application/vnd.openxmlformats-officedocument.theme+xml");
addRelationship(relsDoc, mkId(++idN), R_NS + "/theme", dest.replace(/^word\//, ""));
}
carried.push("theme");
}
}
// Any media extension the carried parts brought with them needs a Default
// entry or Word rejects the package.
for (const dest of usedMedia.values()) {
const ext = (dest.split(".").pop() || "").toLowerCase();
const mime = { png: "image/png", jpeg: "image/jpeg", jpg: "image/jpeg", gif: "image/gif",
bmp: "image/bmp", tiff: "image/tiff", svg: "image/svg+xml",
emf: "image/x-emf", wmf: "image/x-wmf" }[ext];
if (mime) addDefaultExt(ctDoc, ext, mime);
}
// --- rewrite the parts we changed ------------------------------------
if (newRefs.length || (setup && setup.titlePg)) {
const docText = await textOf(gen, "word/document.xml");
const docDoc = parseXml(docText);
injectSectionRefs(docDoc, newRefs, setup && setup.titlePg);
gen.file("word/document.xml", serializeXml(docDoc));
}
gen.file("[Content_Types].xml", serializeXml(ctDoc));
gen.file("word/_rels/document.xml.rels", serializeXml(relsDoc));
const bytes = await gen.generateAsync({
type: "uint8array",
compression: "DEFLATE",
compressionOptions: { level: 6 },
mimeType: "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
});
return { bytes, carried };
}
return { loadZip, scan, graft, readSectionSetup, readCoreProps, parseXml, serializeXml, FEATURES };
});