FontData

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The FontData interface of the Local Font Access API represents a single local font face.

Instance properties

FontData.family Read only

Returns the family of the font face.

FontData.fullName Read only

Returns the full name of the font face.

FontData.postscriptName Read only

Returns the PostScript name of the font face.

FontData.style Read only

Returns the style of the font face.

Instance methods

FontData.blob()

Returns a Promise that fulfills with a Blob containing the raw bytes of the underlying font file.

Examples

For a working live demo, see Font Select Demo.

Font enumeration

The following snippet will query for all available fonts, and log metadata. This could be used, for example, to populate a font-picker control.

js
async function logFontData() {
  try {
    const availableFonts = await window.queryLocalFonts();
    for (const fontData of availableFonts) {
      console.log(fontData.postscriptName);
      console.log(fontData.fullName);
      console.log(fontData.family);
      console.log(fontData.style);
    }
  } catch (err) {
    console.error(err.name, err.message);
  }
}

Accessing low-level data

The blob() method provides access to low-level SFNT data — this is a font file format that can contain other font formats, such as PostScript, TrueType, OpenType, or Web Open Font Format (WOFF).

js
async function computeOutlineFormat() {
  try {
    const availableFonts = await window.queryLocalFonts({
      postscriptNames: ["ComicSansMS"],
    });
    for (const fontData of availableFonts) {
      // `blob()` returns a Blob containing valid and complete
      // SFNT-wrapped font data.
      const sfnt = await fontData.blob();
      // Slice out only the bytes we need: the first 4 bytes are the SFNT
      // version info.
      // Spec: https://learn.microsoft.com/en-us/typography/opentype/spec/otff#organization-of-an-opentype-font
      const sfntVersion = await sfnt.slice(0, 4).text();

      let outlineFormat = "UNKNOWN";
      switch (sfntVersion) {
        case "\x00\x01\x00\x00":
        case "true":
        case "typ1":
          outlineFormat = "truetype";
          break;
        case "OTTO":
          outlineFormat = "cff";
          break;
      }
      console.log("Outline format:", outlineFormat);
    }
  } catch (err) {
    console.error(err.name, err.message);
  }
}

Specifications

Specification
Local Font Access
# fontdata-interface

Browser compatibility

BCD tables only load in the browser

See also