基本功能：

显示所有待办列表（点击不同的文本进行显示）

没完成的待办

已完成的待办

新建待办test

清除待办foo

代码js文件：

//index.js
//获取应用实例
const app = getApp();
Page({data: {todo: '',todos: [{"id": 1474894720002,"todo": "foo","completed": false},{"id": 1474894720922,"todo": "bar","completed": true},{"id": 1474894723594,"todo": "baz","completed": false}],filterTodos: [],filter: 'all',activeCount: 0,},bindTodoInput(e) {this.setData({todo: e.detail.value});},saveTodo(e) {if (this.data.todo.trim().length === 0) {return;}const newTodo = {id: new Date().getTime(),todo: this.data.todo,completed: false,};this.setData({todo: '',todos: this.data.todos.concat(newTodo),filterTodos: this.data.filterTodos.concat(newTodo), activeCount: this.data.activeCount + 1,});},todoFilter(filter, todos) {return filter === 'all' ? todos: todos.filter(x => x.completed === (filter !== 'active'));},toggleTodo(e) {const { todoId } = e.currentTarget.dataset;const { filter, activeCount } = this.data;let { todos } = this.data;let completed = false;todos = todos.map(todo => {if (Number(todoId) === todo.id) {todo.completed = !todo.completed;completed = todo.completed;}return todo;});const filterTodos = this.todoFilter(filter, todos);this.setData({todos,filterTodos,activeCount: completed ? activeCount - 1 : activeCount + 1,});},useFilter(e) {const { filter } = e.currentTarget.dataset;const { todos } = this.data;const filterTodos = this.todoFilter(filter, todos);this.setData({filter,filterTodos,});},clearCompleted() {const { filter } = this.data;let { todos } = this.data;todos = todos.filter(x => !x.completed);this.setData({todos,filterTodos: this.todoFilter(filter, todos),});},todoDel(e) {const { todoId } = e.currentTarget.dataset;const { filter, activeCount } = this.data;let { todos } = this.data;const todo = todos.find(x => Number(todoId) === x.id);todos = todos.filter(x => Number(todoId) !== x.id);this.setData({todos,filterTodos: this.todoFilter(filter, todos),activeCount: todo.completed ? activeCount : activeCount - 1,});},onLoad() {console.log('onLoad');const that = this;const activeCount = this.data.todos.map(x => x.completed ? 0 : 1).reduce((a, b) => a + b, 0);that.setData({activeCount,filterTodos: this.data.todos});}
});

wxml：

<scroll-view class="container" scroll-y="true"><view class="todo"><input class="new-todo"placeholder="添加待办列表"value="{{todo}}"bindinput="bindTodoInput"/><button type="primary" class="new-todo-save" bindtap="saveTodo">→</button></view><view class="todo-footer"><text class="total">{{activeCount}} 个待办</text><view class="filter"><text bindtap="useFilter"data-filter="all"class="{{ filter === 'all' ? 'filter-item filter-active' : 'filter-item'}}">所有</text><text bindtap="useFilter"data-filter="active"class="{{ filter === 'active' ? 'filter-item filter-active' : 'filter-item'}}"       >待办</text><text bindtap="useFilter"data-filter="completed"class="{{ filter === 'completed' ? 'filter-item filter-active' : 'filter-item'}}">已完成</text></view><text wx:if="{{ todos.length - activeCount != 0 }}" class="clear" bindtap="clearCompleted">清除完成项</text><text wx:else class="clear-empty"></text></view><view class="todo-list"><view class="todo-item" wx:for="{{filterTodos}}" wx:key="id"><icon bindtap="toggleTodo" class="todo-check"data-todo-id="{{item.id}}"type="{{ item.completed ? 'success_circle' : 'circle'}}" /><text class="{{ item.completed ? 'todo-content todo-completed' : 'todo-content'}}">{{item.todo}}</text><icon bindtap="todoDel" class="todo-del" data-todo-id="{{item.id}}" type="cancel" /></view></view>
</scroll-view>

wxss:

/**index.wxss**/
.todo {margin: 20rpx;display: flex;align-items: center;background: #F5F5F5;height: 70rpx;
}.new-todo {border: none;font-style: italic;width: 100%;
}.new-todo-save {font-size: 28rpx
}.todo-list {margin: 20rpx;display: flex;flex-direction: column;flex-grow: 2;
}.todo-item {display: flex;height: 80rpx;position: relative;
}.todo-check {margin-top: -6rpx;
}.todo-del {margin-top: -6rpx;position: absolute;right: 20rpx;
}.todo-content {margin-left: 20rpx;
}.todo-completed {color: #d9d9d9;text-decoration: line-through;
}.todo-footer {display: flex;align-items: center;justify-content: space-between;height: 80rpx;margin-left: 20rpx;margin-right: 20rpx;font-size: 24rpx;
}.filter {display: flex;flex-direction: row;
}.filter-item {margin-left: 10rpx;padding: 6rpx 14rpx;
}.filter-active {border: 1px solid;border-color: rgba(175, 47, 47, 0.2);
}.clear-empty {width: 120rpx;height: 24rpx;
}