How to add HTML Tag in dcc.textarea

I want to add some keywords with different color in dcc.textarea’s value, so I use visdcc to add Javascript and it helps me to identify the keywords, but the HTML style does not work. My code just like it.
var ta = document.getElementById(‘textarea_id’);
var i, len = words.length, re;
for (i = 0; i < len; i++) {
re = new RegExp(words[i], ‘g’);
if (re.test(text)) {
text = text.replace(re, ‘$1’);
And if I change the last line as

It doesn’t work either.

Looking forward kindly help. THX…!!!