JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//wzrd.in/standalone/expect@latest"></script>
<script src="//wzrd.in/standalone/deep-freeze@latest"></script>
<body>
</body>

JavaScript

const range = (start, end) => {  
  const size = end ? end - start : start;
  start = end ? start : 0;
  return Array.from(Array(size)).map((_, i) => start + i);
};

const rangeAlpha = (start, stop)  => {
		start = start.charCodeAt(0)
    stop = stop.charCodeAt(0)
    return Array.from(range(start, stop + 1)).map(code => String.fromCharCode(code));
};

const testRangeAlpha = () => {
   expect(
     rangeAlpha('A', 'C').join('')
   ).toEqual('ABC');
  
};

const logAndDisplay = (arg) => {
	document.querySelector('body').innerHTML = arg;
  console.log(arg)
};

testRangeAlpha();
logAndDisplay('All tests passed');