JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <center>
        <div style="width:500px; text-align:left; margin-bottom:10px ">
            <input type="button" id="bold" style="height:21px; width:21px; font-weight:bold;" value="B" onClick="fontEdit('bold')" />
            <input type="button" id="italic" style="height:21px; width:21px; font-style:italic;" value="I" onClick="fontEdit('italic')" />
            <input type="button" id="underline" style="height:21px; width:21px; text-decoration:underline;" value="U" onClick="fontEdit('underline')" /> | 
            <input type="button" style="height:21px; width:21px;"value="L" onClick="fontEdit('justifyleft')" title="align left" />
            <input type="button" style="height:21px; width:21px;"value="C" onClick="fontEdit('justifycenter')" title="center" />
            <input type="button" style="height:21px; width:21px;"value="R" onClick="fontEdit('justifyright')" title="align right" /> | 
            <select id="fonts" onChange="fontEdit('fontname',this[this.selectedIndex].value)">
                <option value="Arial">Arial</option>
                <option value="Comic Sans MS">Comic Sans MS</option>
                <option value="Courier New">Courier New</option>
                <option value="Monotype Corsiva">Monotype</option>
                <option value="Tahoma">Tahoma</option>
                <option value="Times">Times</option>
            </select>
            <select id="size" onChange="fontEdit('fontsize',this[this.selectedIndex].value)">
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>
                <option value="4">4</option>
                <option value="5">5</option>
            </select>
            <select id="color" onChange="fontEdit('ForeColor',this[this.selectedIndex].value)">
                <option value="black">-</option>
                <option style="color:red;" value="red">-</option>
                <option style="color:blue;"...

JavaScript

window.onload = function () {
    window.textEditor = document.getElementById('editor').contentWindow;
    textEditor.document.designMode="on";
    textEditor.document.open();
    textEditor.document.write('<head><style type="text/css">body{ font-family:arial; font-size:13px;}</style></head>');
    textEditor.document.close();
    document.getElementById("fonts").selectedIndex=0;
    document.getElementById("size").selectedIndex=1;
    document.getElementById("color").selectedIndex=0;
    textEditor.document.addEventListener('keyup', showHTML, false);
    textEditor.document.addEventListener('paste', showHTML, false);
}
function showHTML () {
    document.getElementById('textpad').textContent = textEditor.document.body.innerHTML;
    return;
}
function fontEdit(x,y) {
    textEditor.document.execCommand(x,"",y);
    showHTML();
    textEditor.focus();
    
}