JSFiddle - React, Tailwind, and code Playground

HTML

Aoccdrnig to a rscheearch at <b>Cmabrigde Uinervtisy</b>, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the <i>frist</i> and <i>lsat</i> ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a <u>wlohe</u>.

JavaScript

function shuffle(letters) {
    var i = letters.length - 2;
    while (i > 1) {
        var pos = Math.floor(Math.random() * i) + 1;
        var tmp = letters[i];
        letters[i] = letters[pos];
        letters[pos] = tmp;
        i--;
    }
}

function scramble(word) {
    if (word.slice(1, -2) == word.slice(2, -1)) {
        return word;
    }
    var letters = word.split('');
    var result = word;
    while (result == word) {
        shuffle(letters);
        result = letters.join('');
    }
    return result;
}

function process(node) {
    var data = node.data;
    if (/[a-z]{4}/i.test(data)) {
        node.data = data.replace(/[a-z]{4,}/gi, scramble);
    }
}

function traverse(element) {
    var node = element.firstChild;
    while (node) {
        if (node.nodeType == Node.ELEMENT_NODE) {
            traverse(node);
        } else if (node.nodeType == Node.TEXT_NODE) {
            process(node);
        }
        node = node.nextSibling;
    }
}

function garble() {
    traverse(document.body);
}

window.onload = garble;