Mammoth .docx to HTML converter

Mammoth is designed to convert .docx documents, such as those created by Microsoft Word, and convert them to HTML. Mammoth aims to produce simple and clean HTML by using semantic information in the document, and ignoring other details. For instance, Mammoth converts any paragraph with the style Heading1 to h1 elements, rather than attempting to exactly copy the styling (font, text size, colour, etc.) of the heading.

There's a large mismatch between the structure used by .docx and the structure of HTML, meaning that the conversion is unlikely to be perfect for more complicated documents. Mammoth works best if you only use styles to semantically mark up your document.

Web demo

The easiest way to try out mammoth is to use the web demo:

• Clone this repository
• Run make setup
• Open browser-demo/index.html in a web browser

Installation

npm install mammoth

Usage

CLI

You can convert docx files by passing the path to the docx file and the output file. For instance:

mammoth document.docx output.html

If no output file is specified, output is written to stdout instead.

Images

By default, images are included inline in the output HTML. If an output directory is specified by --output-dir, the images are written to separate files instead. For instance:

mammoth document.docx --output-dir=output-dir

Existing files will be overwritten if present.

Styles

A custom style map can be read from a file using --style-map. For instance:

mammoth document.docx output.html --style-map=custom-style-map

Where custom-style-map looks something like:

p.AsideHeading => div.aside > h2:fresh
p.AsideText => div.aside > p:fresh

Library

In node.js, mammoth can be required in the usual way:

var mammoth = require("mammoth");

To generate a standalone JavaScript file for the browser, use mammoth.browser.js (generate using make setup if it is not already present). This uses any loaded module system. If no module system is found, mammoth is set as a window global.

Basic conversion

To convert an existing .docx file to HTML, use mammoth.convertToHtml:

var mammoth = require("mammoth");

mammoth.convertToHtml({path: "path/to/document.docx"})
    .then(function(result){
        var html = result.value; // The generated HTML
        var messages = result.messages; // Any messages, such as warnings during conversion
    })
    .done();

Note that mammoth.convertToHtml returns a promise.

Custom style map

By default, Mammoth maps some common .docx styles to HTML elements. For instance, a paragraph with the style Heading1 is converted to a h1 element. You can pass in a custom map for styles by passing an options object with a styleMap property as a second argument to convertToHtml. A description of the syntax for style maps can be found in the section "Writing style maps". For instance, if paragraphs with the style SectionTitle should be converted to h1 elements, and paragraphs with the style SubSectionTitle should be converted to h2 elements:

var mammoth = require("mammoth");
var styleMapping = mammoth.styleMapping;

var options = {
    styleMap: [
        styleMapping("p.SectionTitle => h1:fresh"),
        styleMapping("p.SubSectionTitle => h2:fresh")
    ]
};
mammoth.convertToHtml({path: "path/to/document.docx"}, options);

To more easily support style maps stored in text files, styleMap can also be a string. Each non-blank line is treated as a separate style mapping:

var options = {
    styleMap: "p.SectionTitle => h1:fresh\n" +
        "p.SubSectionTitle => h2:fresh"
};

User-defined style mappings are used in preference to the default style mappings. To stop using the default style mappings altogether, set options.includeDefaultStyleMap to false:

var options = {
    styleMap: [
        styleMapping("p.SectionTitle => h1:fresh"),
        styleMapping("p.SubSectionTitle => h2:fresh")
    ],
    includeDefaultStyleMap: false
};

Document transforms

Mammoth allows a document to be transformed before it is converted. For instance, suppose that document has not been semantically marked up, but you know that any centre-aligned paragraph should be a heading. You can use the transformDocument argument to modify the document appropriately:

function transformElement(element) {
  if (element.children) {
      element.children.forEach(transformElement);
  }
  if (element.type === "paragraph") {
      if (element.alignment === "center" && !element.styleName) {
          element.styleName = "Heading2";
      }
  }
  return element;
}

var options = {
    transformDocument: transformElement
};

The return value of transformDocument is used during HTML generation. The original document (and any child elements) can be safely modified.

API

mammoth.convertToHtml(input, options)

Converts the source document to HTML.

• input: an object describing the source document. While running on node.js, to read the file found at path, pass in {path: path}. While running in the browser, to read the file stored in an array buffer, pass in {arrayBuffer: arrayBuffer}.

• options (optional): options for the conversion. May have the following properties:

  • styleMap: controls the mapping of Word styles to HTML. If options.styleMap is a string, each non-blank line is treated as a separate style mapping. If options.styleMap is an array, each element is expected to be the result of a call to mammoth.styleMapping. See "Writing style maps" for a reference to the syntax for style maps.

  • includeDefaultStyleMap: by default, the style map passed in styleMap is combined with the default style map. To stop using the default style map altogether, set options.includeDefaultStyleMap to false.

  • transformDocument: if set, this function is applied to the document read from the docx file before the conversion to HTML.

• Returns a promise containing a result. This result has the following properties:

  • value: the generated HTML

  • messages: any messages, such as errors and warnings, generated during the conversion

mammoth.styleMapping(string)

Creates a style mapping using the passed string.

Messages

Each message has the following properties:

• type: a string representing the type of the message, such as "warning"

• message: a string containing the actual message

Writing style maps

A style map is made up of a number of style mappings separated by new lines.

A style mapping has two parts:

• On the left, before the arrow, is the document element matcher.
• On the right, after the arrow, is the HTML path.

When converting each paragraph, Mammoth finds the first style mapping where the document element matcher matches the current paragraph. Mammoth then ensures the HTML path is satisfied.

Freshness

When writing style mappings, it's helpful to understand Mammoth's notion of freshness. When generating, Mammoth will only close an HTML element when necessary. Otherwise, elements are reused.

For instance, suppose one of the specified style mappings is p.Heading1 => h1. If Mammoth encounters a .docx paragraph with the style Heading1, the .docx paragraph is converted to a h1 element with the same text. If the next .docx paragraph also has the style Heading1, then the text of that paragraph will be appended to the existing h1 element, rather than creating a new h1 element.

In most cases, you'll probably want to generate a new h1 element instead. You can specify this by using the :fresh modifier:

p.Heading1 => h1:fresh

The two consective Heading1 .docx paragraphs will then be converted to two separate h1 elements.

Reusing elements is useful in generating more complicated HTML structures. For instance, suppose your .docx contains asides. Each aside might have a heading and some body text, which should be contained within a single div.aside element. In this case, style mappings similar to p.AsideHeading => div.aside > h2:fresh and p.AsideText => div.aside > p:fresh might be helpful.

Document element matchers

Paragraphs and runs

Match any paragraph:

p

Match any run:

r

To match a paragraph or run with a specific style name, append a dot followed by the style name. For instance, to match a paragraph with the style Heading1:

p.Heading1

HTML paths

Single elements

The simplest HTML path is to specify a single element. For instance, to specify an h1 element:

h1

To give an element a CSS class, append a dot followed by the name of the class:

h1.section-title

To require that an element is fresh, use :fresh:

h1:fresh

Modifiers must be used in the correct order:

h1.section-title:fresh

Nested elements

Use > to specify nested elements. For instance, to specify h2 within div.aside:

div.aside > h2

You can nest elements to any depth.