摘要:发现最近看到的框架入门程序都变成,我花了三个小时才自己实现了一个感叹前端入门越来越复杂了,怀念几年前还是的时代。。。主要负责的渲染,和那个框的功能。利用对的值进行控制,然后监听键盘来判断是输入还是提交。需要讲解的不多。。。
发现最近看到的框架入门程序都变成Todos,我花了三个小时才自己实现了一个Todos...感叹前端入门越来越复杂了,怀念几年前还是hello world的时代。。。
吐槽不多说,这里主要说的只是React和Redux这一块儿,css样式完全是从这里抄过来的。
代码的结构准备是这个样子的:
转化成代码结构,就是这个样子:
另外,按照官方示例,在Header左边的toggleAll按钮放到了Section中。
Redux Types/todos.js在Redux中,type是用于action和reducer交流的时候的一个flag,让reducer知道这是一个什么请求。
我比较习惯把type多带带分离出来,列到一个文件里面,让Redux的文件更干净,并便于管理。
/** ------------------------- TODO ---------------------*/ export const TODO_INSERT_ITEM = "TODO_INSERT_ITEM"; export const TODO_DELETE_ITEM = "TODO_DELETE_ITEM"; export const TODO_SWITCH_FILTER = "TODO_SWITCH_FILTER"; export const TODO_TOGGLE_ACTIVE = "TODO_TOGGLE_ACTIVE"; export const TODO_TOGGLE_ALL = "TODO_TOGGLE_ALL"; export const TODO_CHANGE_VALUE = "TODO_CHANGE_VALUE"; export const TODO_CLEAR_COMPLETED = "TODO_CLEAR_COMPLETED";Actions/todos.js
根据上面列出的type,列出对应的action creator
import { TODO_INSERT_ITEM, TODO_DELETE_ITEM, TODO_SWITCH_FILTER, TODO_TOGGLE_ACTIVE, TODO_TOGGLE_ALL, TODO_CHANGE_VALUE, TODO_CLEAR_COMPLETED } from "../types"; // 插入一个TODO export function insertItem(value){ return { type: TODO_INSERT_ITEM, value }; } // 删除一个TODO export function deleteItem(id) { return { type: TODO_DELETE_ITEM, id } } // 转换一个TODO的状态 export function switchFilter(filter) { return { type: TODO_SWITCH_FILTER, filter } } // 清楚所有完成的TODO export function clearCompleted(){ return { type: TODO_CLEAR_COMPLETED } } export function toggleActive(id){ return { type: TODO_TOGGLE_ACTIVE, id } } // 转换所有的状态到active export function toggleAll(active){ return { type: TODO_TOGGLE_ALL, active } } // 改变对应TODO的值 export function changeValue(id, value) { return { type: TODO_CHANGE_VALUE, id, value } }Reducers/todos.js
在reducer中需要注意几点:
初始化的state要从localStorage中获取
每次做出修改,都要重新更新localStorage
数据没有发生改变的时候,尽量使用原数据,减少re-render
为了便于查找,我在这里用了lodash的uniqueId方法,给每一个item加一个id
为了便于储存和展示,我这里包含一个items用来保存所有的items,一个showedItems用来储存需要展示的items
先提供一个简单的简写localStorage方法
const local = (function(KEY){ return { set: value=>{ localStorage.setItem(KEY, value) }, get: ()=>localStorage.getItem(KEY), check: ()=>localStorage.getItem(KEY) != undefined }; })("todo");
然后几个辅助的方法:
// 制造一个新的item function generateItem(value) { return { id: _.uniqueId(), active: true, value } } // 判断当前的item是否正在展示 function include(active, filter) { return filter === "ALL" || (active && filter === "ACTIVE") || (!active && filter === "COMPLETED"); } // 获取页面上需要展示的items function getShowedItems(items, filter) { let showedItems = [], keys = Object.keys(items); for(let i = 0; i < keys.length; i++){ let item = items[keys[i]]; if(include(item.active, filter)) { showedItems.push(item); } } return showedItems; }
初始化的时候,获取localStorage中的值,或者给一个默认值:
let defaultTodo; (function(){ if(local.check()) { defaultTodo = JSON.parse(local.get()); } else { defaultTodo = { items: {}, filter: "ALL", // ALL, COMPLETED, ACTIVE count: 0, showedItems: [], hasCompleted: false } } })();
注:在这里提一句,由于我不喜欢文档中把所有的处理方法放在一个函数里面的方式,所以我写了一个方法,把reducers分开成多个函数
// 很简单,其实就是循环调用。。。 export function combine(reducers){ return (state, action) => { for(let key in reducers) { if(reducers.hasOwnProperty(key)) { state = reducers[key](state, action) || state; } } return state; } }
下面上所有的reducers,具体逻辑就不多说了:
let exports = {}; exports.insertItem = function(state = defaultTodo, action) { const type = action.type; if(type === TODO_INSERT_ITEM) { let { count, items, filter, showedItems } = state; let item = generateItem(action.value); items = { ...items, [item.id] : item } count = count + 1; state = { ...state, items, count, showedItems: filter !== "COMPLETED" ? getShowedItems(items, filter) : showedItems } local.set(JSON.stringify(state)); } return state; } exports.deleteItem = function(state = defaultTodo, action) { const type = action.type; if(type === TODO_DELETE_ITEM && state.items[action.id]) { let { count, items, filter, hasCompleted } = state; let item = items[action.id]; delete items[action.id]; if(item.active) count--; state = { ...state, items, count, showedItems: include(item.active, filter) ? getShowedItems(items, filter) : state.showedItems, hasCompleted: Object.keys(items).length !== count } local.set(JSON.stringify(state)); } return state; } exports.switchFilter = function(state = defaultTodo, action) { const type = action.type; if(type === TODO_SWITCH_FILTER && state.filter !== action.filter) { state = { ...state, filter: action.filter, showedItems: getShowedItems(state.items, action.filter) } local.set(JSON.stringify(state)); } return state; } exports.clearCompleted = function(state = defaultTodo, action) { const type = action.type; if(type === TODO_CLEAR_COMPLETED) { let { items, filter, showedItems } = state; let keys = Object.keys(items); let tempItems = {}; for(let i = 0; i < keys.length; i++) { let item = items[keys[i]]; if(item.active) { tempItems[item.id] = item; } } state = { ...state, items: tempItems, showedItems: filter === "ACTIVE" ? showedItems : getShowedItems(tempItems, filter), hasCompleted: false } local.set(JSON.stringify(state)); } return state; } exports.toggleActive = function(state = defaultTodo, action) { const { type, id } = action; if(type === TODO_TOGGLE_ACTIVE && state.items[id]) { let { items, filter, count, showedItems } = state; let item = items[id]; item.active = !item.active; items = { ...items, [id]: item }; if(item.active) count++; // 如果变为active else count--; // 如果变为completed state = { ...state, items, count, showedItems: getShowedItems(items, filter), hasCompleted: Object.keys(items).length !== count } local.set(JSON.stringify(state)); } return state; } exports.toggleAll = function(state = defaultTodo, action) { const { type, active } = action; if(type === TODO_TOGGLE_ALL) { let { items, filter, showedItems } = state; let keys = Object.keys(items); for(let i = 0; i < keys.length; i++) { items[keys[i]].active = active; } let count = active ? keys.length : 0; state = { ...state, items, count, showedItems: include(active, filter) ? getShowedItems(items, filter) : showedItems, hasCompleted: !active } local.set(JSON.stringify(state)); } return state; } exports.changeValue = function(state = defaultTodo, action){ const { type, id } = action; if(type === TODO_CHANGE_VALUE && state.items[id]) { let { items, filter, showedItems } = state; let item = items[id]; item.value = action.value; items = { ...items, [id]: item }; state = { ...state, items, showedItems: include(item.active, filter) ? getShowedItems(items, filter) : showedItems } local.set(JSON.stringify(state)); } return state; } export default combine(exports); // 用combine方法包裹
Reducers中,我在很多的showedItems都做了是否发生改变的检查,如果没有发生改变,那么就用原来的,便于在Section组件中,可以避免不必要的重新渲染。虽然,在我这里似乎没有什么用。不过对复杂的项目还是有必要的。
Views/Todos.jsimport React from "react"; import Header from "containers/ToDo/Header"; import Footer from "containers/ToDo/Footer"; import Section from "containers/ToDo/Section"; import "components/ToDo/index.scss"; export default class ToDo extends React.Component { constructor(props) { super(props); } render(){ return (Contianers Header.js) } }
Header.js主要负责logo的渲染,和那个input框的功能。
利用controlled component对input的值进行控制,然后监听键盘来判断是输入还是提交。
import React from "react"; import { CONTROLS } from "utils/KEYCODE"; import { connect } from "react-redux"; import { insertItem } from "actions/todo"; class Header extends React.Component { constructor(props) { super(props); this.state = { value: "" }; } onChange = (e)=>{ let value = e.target.value; this.setState({ value }); } onKeyDown = (e)=>{ let keyCode = e.keyCode; if(keyCode === CONTROLS.ENTER && this.state.value !== "") { this.props.insertItem(this.state.value); this.setState({ value: "" }); e.preventDefault(); e.stopPropagation(); } } render(){ return (Footer.js) } } export default connect(null, { insertItem })(Header); todos
Footer主要是用于展示数量,filter, Clear Completed按钮
import React, { PropTypes } from "react"; import { connect } from "react-redux"; import { switchFilter, clearCompleted } from "actions/todo"; class Footer extends React.Component { constructor(props) { super(props); } switchFilter = (filter)=>{ this.props.switchFilter(filter.toUpperCase()); } render(){ const { count, hasCompleted, filter, clearCompleted } = this.props; if(count === 0 && !hasCompleted) return null; return ( ) } } Footer.propTypes = { count: PropTypes.number.isRequired, hasCompleted: PropTypes.bool.isRequired, filter: PropTypes.oneOf(["ALL", "ACTIVE", "COMPLETED"]).isRequired } function mapStateToProps(state){ let { todo: { count, hasCompleted, filter } } = state; return { count, hasCompleted, filter } } export default connect(mapStateToProps, { switchFilter, clearCompleted })(Footer);Section.js
Section包含Todos的列表,还有删除, 改变状态,修改value, toggle all等功能。
import React, { PropTypes } from "react"; import { connect } from "react-redux"; import { deleteItem, toggleActive, toggleAll, changeValue } from "actions/todo"; import Item from "components/ToDo/Item"; class Section extends React.Component { constructor(props) { super(props); } render(){ const { showedItems=[], count, toggleAll, changeValue, deleteItem, toggleActive, hasCompleted } = this.props; return (Components Item.js{ toggleAll(count === 0) }} checked={count === 0 && hasCompleted} /> ) } } Section.propTypes = { showedItems: PropTypes.arrayOf(PropTypes.object).isRequired, count: PropTypes.number.isRequired } function mapStateToProps(state) { let { todo: { showedItems, count, hasCompleted } } = state; return { showedItems, count, hasCompleted }; } export default connect(mapStateToProps, { deleteItem, toggleActive, toggleAll, changeValue })(Section);{ showedItems.map(item=>
- ) }
import React from "react"; import ReactDOM from "react-dom"; export default class Item extends React.Component { constructor(props) { super(props); this.state = { value: props.value, editing: false }; } componentDidUpdate() { if(this.state.editing) { var node = ReactDOM.findDOMNode(this.edit); node.focus(); } } inputInstance = (input) => { this.edit = input; } onToggle = (e)=>{ this.props.toggleActive(this.props.id, !e.target.checked); } onValueChange = (e)=>{ this.props.onValueChange(this.props.id, e.target.value); this.setState({ editing: false }); } onEditChange = (e)=>{ this.setState({ value: e.target.value }); } onDoubleClick = (e)=>{ this.setState({ editing: true }); } render(){ let { id, active, onItemDelete, onValueChange } = this.props; let { value, editing } = this.state; return (
写组件的时候,感觉代码贴出来看看就好了。需要讲解的不多。。。
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