Load font async, only support woff2, woff source

FontFace load

function load(family, source, descriptors) {
    if (typeof FontFace.prototype.load === 'function') {
        return new FontFace(family, source, descriptors)
            .load()
    } else {
        const regex = /url\((.*?)\)(.*\('(.*?)'\))?/
        const srcset = source
            .split(",")
            .map(src => {
                const matches = src.match(regex);
                return {
                    url: matches[1],
                    format: matches[3] || matches[1].substring(matches[1].lastIndexOf(".") + 1)
                }
            })
        return fetch(srcset.find(src => src.format === 'woff').url)
            .then(resp => resp.arrayBuffer())
            .then(buffer => new FontFace(family, buffer, descriptors));
    }
}

usage:
load(family, source, descriptors).then(font => document.fonts.add(font));

source support multi url, url(xxx.woff2) format('woff2'),url(xxx.woff) format('woff')