1.添加 ng-click="delete($index)

 <!--标签内容-->
<div class="list_body active">
    <ul>
        <li class="item" ng-repeat="item in taskList">
            ...
            <!--注册删除事件-->
            <span class="del" ng-click="delete($index)">删除</span>
            <span class="detail">详情</span>
        </li>
    </ul>
</div>

2.添加删除方法 index.js

app.controller('taskController', ['$scope', function ($scope) {
    ...
    //定义删除方法
    $scope.delete = function (key) {
        //删除key元素, 删除1个
        $scope.taskList.splice(key, 1);
    }

}]);