get sub font from ttf file

subsetfont

const fs = require('fs');
const util = require("util");
const fontKit = require("font-toolkit");

const readFile = util.promisify(fs.readFile);
const writeFile = util.promisify(fs.writeFile);

async function save() {
    // read font
    const buf = await readFile("20th_bold.ttf");
    const srcFont = new fontKit.Font(buf);
    srcFont.satisfy();

    // minify
    const mini = new fontKit.Minifier(srcFont);
    const newFont = mini.with("1234567890/");

    // write to buf
    const wb = new fontKit.BufferWriter();
    newFont.write2(wb);

    await writeFile("number.ttf", wb.buffer);
}

save()