extract_characters_by_font.js

function extract_characters_by_font(font_name) {
    var allElems = document.querySelectorAll('*');
    var characters = Array.prototype
            .filter.call(allElems, function (elem) {
                var fonts = getComputedStyle(elem)['font-family'].split(',').map(function(font){
                    return font.trim().replace(/'/g,'');
                });
                return fonts.indexOf(font_name) > -1;
            })
            .map(function (elem) {
                return elem.innerText.trim();
            })
            .join('')
            .replace(/\s/g, '')
            .split('');

    var charactersString = Array.from(new Set(characters)).join('');
    return charactersString;
}

var font_name = '07YasashisaAntique';
copy(extract_characters_by_font(font_name));