You can load an external font with jquery
$('div').on('click', function(){
$('textarea').css({'font-family': 'fonte',
"src": "url(https://fonts.gstatic.com/s/tangerine/v8/HGfsyCL5WASpHOFnouG-RFtXRa8TVwTICgirnJhmVJw.woff2)"
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<textarea>Depois de 10 anos o menino virou adulto.</textarea>
<div>Clique para mudar a fonte</div>The code below can help you. For more details, take a look at this link: HERE
$('div').on('click', function(){
$("head").prepend("<style type=\"text/css\">" +
"@font-face {\n" +
"\tfont-family: \"fonte\";\n" +
"\tsrc: local('☺'), url('fonte.otf') format('opentype');\n" +
"}\n" +
"\tp.myClass {\n" +
"\tfont-family: fonte !important;\n" +
"}\n" +
"</style>");
});