Editing HTML 编码

<!DOCTYPE html>
<html>

<head>
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta charset="utf-8" />
    <title>HTML 编码</title>
</head>

<body>
    <textarea rows="9" style="width:99%" placeholder="粘贴 HTML 内容" ></textarea>
    <button class="btn-regex">regex</button>
    <button class="btn-html">html</button>

    <p><a target="_blank" href="https://stackoverflow.com/questions/18749591">SO#18749591</a></p>

    <pre class="view-html"></pre>
</body>

</html>

var domTxt = document.querySelector('textarea');
domTxt.value = document.documentElement.outerHTML;

var domView = document.querySelector('.view-html');

document.querySelector('.btn-html').addEventListener('click', () => {
    console.time();
    var div = document.createElement("div");
    div.innerText = domTxt.value;
    domTxt.value = div.innerHTML.replaceAll('<br>', '\r\n')
    domView.innerHTML = domTxt.value;
    console.timeEnd();
})

document.querySelector('.btn-regex').addEventListener('click', () => {
    console.time();
    domTxt.value = domTxt.value.replace(/[\u00A0-\u9999<>\&]/g, function (i) {
        return '&#' + i.charCodeAt(0) + ';';
    })
    domView.innerHTML = domTxt.value;
    console.timeEnd();
})