JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id=t></textarea>
<pre id=o></pre>

JavaScript

$('#t').click(function(){
    var o = {}
    $('#t').prop('value').split('').forEach(function(c){ o[c] = (o[c] || 0) + 1})
    var txt = ''
    for (var k in o) txt += k + ': ' + o[k] + '\n'
    $('#o').text(txt)
})