Typoglycemia.js http://en.wikipedia.org/wiki/Typoglycemia

typoglycemia.js

function scramble(input) {
  return input.replace(/\b(\w)(\w{2,})(\w)\b/g, function(all, a, b, c) {
    return a
      + b.split('').sort(function(){return Math.random()-.2}).join('')
      + c;
  });
}

input = prompt("Enter the message you want scrambled:");
console.log(scramble(input));