Edit in JSFiddle

function DemoCtrl($scope) {
  //先預設給畫面上的待辦清單資料
  $scope.title = '我的待辦清單';

  //給ng-repeat使用的資料列表，預設為空陣列
  $scope.dataList = [];

  //監聽事件
  $scope.$watch('dataList', function() {
    $scope.updateCount();
  }, true);

  //更新 待辦事項總數量/完成待辦數量/未完成待辦數量 事件
  $scope.updateCount = function() {
    //先把數量歸0
    $scope.allCount = 0;
    $scope.finishCount = 0;
    $scope.unfinishCount = 0;
    angular.forEach($scope.dataList, function(item) {
      $scope.allCount++;
      if (item.checked) {
        $scope.finishCount++;
      } else {
        $scope.unfinishCount++;
      }
    })
  }

  //定義刪除事件
  $scope.delete = function(index) {
    //對array物件刪除元素
    $scope.dataList.splice(index, 1);
  }

  //定義新增事件
  $scope.add = function() {
    if ($scope.newEvent == '') {
      alert('請輸入待辦事項');
    } else {
      var data = {
        checked: false,
        name: $scope.newEvent
      }
      $scope.dataList.push(data)
      $scope.newEvent = '';
    }
  }
}

<div ng-app>
  <div ng-controller="DemoCtrl">
    <!-- 標題 -->
    <h2>{{title}}</h2>

    <!-- 副標題 -->
    <h3>共{{allCount || 0}}項事件，已完成{{finishCount || 0}}項，未完成{{unfinishCount || 0}}項</h3>

    <!-- Todo列表 -->
    <div>
      <h4>待辦事項</h4>
      <!-- ng-repeat開始 -->
      <li ng-repeat="item in dataList">
        <input type='checkbox' ng-model="item.checked" ng-checked="allchecked" /> {{item.name}}
        <input type='button' value='刪除' ng-click="delete($index)">
      </li>
      <!-- ng-repeat結束 -->
    </div>

    <!-- 新增事件 -->
    <div>
      <h4>新增待辦事項</h4>
      <input type='text' ng-model='newEvent'>
      <input type='button' value='新增' ng-click='add()'>
    </div>
  </div>
</div>