Todo mvc js edit method

edit.js

  edit: function (event) {
    var labelEl = event.target;
    var liEl = labelEl.closest('li');
    var inputEl = liEl.lastElementChild;
    var len = inputEl.value.length;

    liEl.className = 'editing';

    inputEl.focus();
    inputEl.setSelectionRange(len, len);
  }