Convert *bold* and _italics_ into unicode

tester.js

function cp(c) {
  return c.codePointAt(0);
}

function base(c) {
  if (/[a-z]/.test(c)) {
    return [cp('a'), cp('𝗮'), cp('𝘢')];
  } else if (/[A-Z]/.test(c)) {
    return [cp('A'), cp('𝗔'), cp('𝘈')];
  }
}

function format(str, baseIndex) {
  return str.split('')
    .map(function(s) {return base(s) ? String.fromCodePoint(cp(s) - base(s)[0] + base(s)[baseIndex]) : s}).join('');
}

const bold = function(str) {return format(str, 1);}; 
const italic = function(str) {return format(str, 2);}; 

function transform(str) {
  return str.replace(/_([^_]*)_/g, function(_, c) { return italic(c); }).replace(/\*([^\*]*)\*/g, function(_, c) { return bold(c);});
}

function copyToClipboard(str) {
  const el = document.createElement('textarea');
  el.value = str;
  document.body.appendChild(el);
  el.select();
  document.execCommand('copy');
  document.body.removeChild(el);
};

navigator.clipboard.readText().then(function(text) {
  copyToClipboard(transform(text))
});


function output(str) {
  document.getElementById("out").innerHTML = str;
}

output(transform("_this_ *IS* a *test* _ABCDE_ and *AGAIN* _DEFGH_"))