Use jQuery for element construction

LetUsAppend.js

var createMyWrappedInput = function (defaultValue) {
  var wrapper = $("<div class='Wrapper'></div>"),
      input = $('<input type="text" />');

  input.val(defaultValue);
  wrapper.append(input);

  return wrapper;
};

One other note: If you're finding yourself using lots of concatenation or appending, try using jQuery-tmpl which allows you to create HTML templates that you can populate with data (similar to Django templates).