微信小程序跨页面数据传递事件响应实现过程解析

function isFunc(fn) {
 return typeof fn === 'function';
}

export default class Emitter {
 constructor() {
 this._store = {};
 }

 /**
 * 事件监听
 * @param {String} event 事件名
 * @param {Function} listener 事件回调函数
 */
 on(event, listener) {
 const listeners = this._store[event] || (this._store[event] = []);

 listeners.push(listener);
 }

 /**
 * 取消事件监听
 * @param {String} event 事件名
 * @param {Function} listener 事件回调函数
 */
 off(event, listener) {
 const listeners = this._store[event] || (this._store[event] = []);

 listeners.splice(listeners.findIndex(item => item === listener), 1);
 }

 /**
 * 事件监听 仅监听一次
 * @param {String} event 事件名
 * @param {Function} listener 事件回调函数
 */
 once(event, listener) {
 const proxyListener = (data) => {
  isFunc(listener) && listener.call(null, data);

  this.off(event, proxyListener);
 }

 this.on(event, proxyListener);
 }

 /**
 * 触发事件
 * @param {String} 事件名
 * @param {Object} 传给事件回调函数的参数
 */
 emit(event, data) {
 const listeners = this._store[event] || (this._store[event] = []);

 for (const listener of listeners) {
  isFunc(listener) && listener.call(null, data);
 }
 }
}

export class Storage {
 constructor() {
 this._store = {};
 }

 add(key, val) {
 this._store[key] = val;
 }
 
 get(key) {
 return this._store[key];
 }
 
 remove(key) {
 delete this._store[key];
 }
 
 clear() {
 this._store = {};
 }
}

export default new Storage();

<template>
 <div class="page">
 <div class="weui-cells__title">选择城市</div>
 <div class="weui-cells weui-cells_after-title">
  <navigator :url="`../select/select?id=${cityId}`" class="weui-cell weui-cell_access" hover-class="weui-cell_active">
  <div class="weui-cell__hd weui-label">所在城市</div>
  <div class="weui-cell__bd" :style="{color: cityName || '#999'}">{{ cityName || '请选择' }}</div>
  <div class="weui-cell__ft weui-cell__ft_in-access"></div>
  </navigator>
 </div>
 </div>
</template>

<script>
import Emitter from '../../utils/emitter';
import storage from '../../utils/storage';

export default {
 data() {
 return {
  cityId: '',
  cityName: '',
 }
 },
 onLoad() {
 const emitter = new Emitter();

 // 将emitter存到storage中
 storage.add('indexEmitter', emitter);

 // 添加事件监听
 emitter.on('onSelect', this.handleSelect);
 },
 methods: {
 // 事件处理
 handleSelect(data) {
  this.cityId = data.id;
  this.cityName = data.text;
 }
 }
}
</script>

<template>
 <div class="page">
 <div class="weui-cells__title">城市列表</div>
 <div class="weui-cells weui-cells_after-title">
  <radio-group @change="handleChange">
  <label class="weui-cell weui-check__label" v-for="item in list" :key="item.id">
   <radio class="weui-check" :value="item.id" :checked="`${item.id}` === selectedId" />
   <div class="weui-cell__bd">{{ item.text }}</div>
   <div v-if="`${item.id}` === selectedId" class="weui-cell__ft weui-cell__ft_in-radio">
   <icon class="weui-icon-radio" type="success_no_circle" size="16" />
   </div>
  </label>
  </radio-group>
 </div>
 </div>
</template>

<script>
import storage from '../../utils/storage';

export default {
 data() {
 return {
  list: [
  { id: 0, text: '北京' },
  { id: 1, text: '上海' },
  { id: 2, text: '广州' },
  { id: 3, text: '深圳' },
  { id: 4, text: '杭州' },
  ],
  selectedId: ''
 }
 },
 onLoad({ id }) {
 this.selectedId = id;
 
 // 取出 emitter
 this.emitter = storage.get('indexEmitter');
 },
 methods: {
 handleChange(e) {
  this.selectedId = e.detail.value;

  const item = this.list.find(({ id }) => `${id}` === e.detail.value);

  // 触发事件并传递数据
  this.emitter.emit('onSelect', { ...item });
 }
 }
}
</script>