Subfont

Command line tool to optimize your webfont loading. Aggressive subsetting b...

Font
Munter/subfontsubfont

README

subfont

NPM version Build Status Coverage Status Dependency Status Greenkeeper badge

A command line tool to statically analyse your page in order to generate the most optimal web font subsets, then inject them into your page.

Speed up your time to first meaningful paint by reducing the web font payload and critical path to the font files.

Subfont will:

- Automatically figure out what characters are used from each font
- Warn you about usage of characters that don't exist as glyphs in your webfonts
- Create an exact subset of used characters of each font
- Generate web fonts in both woff2 and woff formats
- Add preload hints for the subsets to reduce time to first meaningful paint
- Add JS font loading for browsers without preload support
- Give the subsetted fonts new names and prepend them in front of the original fonts in your font-family definitions (enables missing glyph fallback)
- Async load your original @font-face declaring CSS at the bottom of your page, moving it off the critical path

A site before and after running subfont

Currently supported font services:

- Google fonts
- Local fonts (with fonttools)

If you know of font services with liberal font usage licenses, open an issue and we'll add support for them

Installation


Get the basic CLI tool, which supports subsetting Google Fonts and optimizing all local fonts with preloading instructions:

  1. ```
  2. npm install -g subfont
  3. ```

Recommended usage


Run subfont on the files you are ready to deploy to a static file hosting service. If these are build artifacts from another build system, and not the original files, run subfont path/to/artifacts/index.html -i to have subfont clobber the dist files in their original location.

If you want to run directly against your raw original files, it is recommended to create a recursive copy of your files which you run subfont on. This keeps your original authoring abstraction unchanged.

Including additional characters in the subsets


If you have a use case where the automatic tracing doesn't find all the characters you need, you can tell subfont to include specific characters in the subsets by adding a custom -subfont-text property to the respective @font-face declarations.

Example where all numerical digits are added to the bold italic Roboto variant:

  1. ```css
  2. @font-face {
  3.   font-family: Roboto;
  4.   font-style: italic;
  5.   font-weight: 700;
  6.   src: url(roboto.woff) format('woff');
  7.   -subfont-text: '0123456789';
  8. }
  9. ```

An easier, but less fine-grained option is to use the --text switch to include a set of characters in all created subsets.

Other usages


You can have subfont output a copy of your input files to a new directory. This uses Assetgraph to trace a dependency graph of your website and writes it to your specified output directory. Be aware of any errors or warnings that might indicate Assetgraph having problems with your code, and be sure to double check that the expected files are in the output directory. Runsubfont path/to/index.html -o path/to/outputDir.

You can also have subfont scrape a website directly using http and write the output to local disk. This use is likely to fail in a number of ways and should mostly considered a demo feature if you just want to give the tool a quick go to see what it will do to your page. Run subfont https://yourpage.me -o path/to/outputDir.

Command line options


  1. ```
  2. $ subfont --help
  3. Create optimal font subsets from your actual font usage.
  4. subfont [options] <htmlFile(s) | url(s)>

  6. Options:
  7.   --help                             Show help                                           [boolean]
  8.   --version                          Show version number                                 [boolean]
  9.   --root                             Path to your web root (will be deduced from your input files
  10.                                      if not specified)                                    [string]
  11.   --canonical-root, --canonicalroot  URI root where the site will be deployed. Must be either an
  12.                                      absolute, a protocol-relative, or a root-relative url[string]
  13.   --output, -o                       Directory where results should be written to         [string]
  14.   --browsers                         Override your projects browserslist configuration to specify
  15.                                      which browsers to support. Controls font formats and
  16.                                      polyfill. Defaults to browserslist's default query if your
  17.                                      project has no browserslist configuration            [string]
  18.   --formats                          Font formats to use when subsetting. The default is to select
  19.                                      the formats based on the browser capabilities as specified
  20.                                      via --browsers or the browserslist configuration.
  21.                                                     [array] [choices: "woff2", "woff", "truetype"]
  22.   --text                             Additional characters to include in the subset for every
  23.                                      @font-face found on the page                         [string]
  24.   --fallbacks                        Include fallbacks so the original font will be loaded when
  25.                                      dynamic content gets injected at runtime. Disable with
  26.                                      --no-fallbacks                      [boolean] [default: true]
  27.   --dynamic                          Also trace the usage of fonts in a headless browser with
  28.                                      JavaScript enabled                 [boolean] [default: false]
  29.   --in-place, -i                     Modify HTML-files in-place. Only use on build artifacts
  30.                                                                         [boolean] [default: false]
  31.   --inline-css                       Inline CSS that declares the @font-face for the subset fonts
  32.                                                                         [boolean] [default: false]
  33.   --font-display                     Injects a font-display value into the @font-face CSS.
  34.              [string] [choices: "auto", "block", "swap", "fallback", "optional"] [default: "swap"]
  35.   --recursive, -r                    Crawl all HTML-pages linked with relative and root relative
  36.                                      links. This stays inside your domain
  37.                                                                         [boolean] [default: false]
  38.   --relative-urls                    Issue relative urls instead of root-relative ones
  39.                                                                         [boolean] [default: false]
  40.   --silent, -s                       Do not write anything to stdout    [boolean] [default: false]
  41.   --debug, -d                        Verbose insights into font glyph detection
  42.                                                                         [boolean] [default: false]
  43.   --dry-run, --dry, --dryrun         Don't write anything to disk       [boolean] [default: false]
  44. ```

Other great font tools


https://meowni.ca/font-style-matcher/

License


MIT