.
├── query-node.js
├── waterfall-item.js
├── waterfall-item.json
├── waterfall-item.wxml
├── waterfall-item.wxss
├── waterfall.js
├── waterfall.json
├── waterfall.wxml
└── waterfall.wxss

// waterfall.js
Component({
 // ... other code
 relations: {
 './waterfall-item': {
  type: 'child',
 },
 // ... other code
 }
})

// waterfall-item.js
Component({
 // ... other code
 relations: {
 '././waterfall': {
  type: 'parent',
 },
 // ... other code
 }
})

<view class="waterfall custom-class">
 <view class="waterfall-inner">
 <slot ></slot>
 </view>
</view>

<view
 class="waterfall-item custom-class"
 style="{{position}}:0;top:{{(top >= 0 ? top + 'px' : 0 + 'rpx')}};"
>
 <slot ></slot>
</view>

// query-node.js
/**
 * 獲取當前頁面中，選擇器為 selector 的第一個node節(jié)點
 * @param {String} selector 符合微信小程序規(guī)范的選擇器
 * @param {Object} context 調(diào)用環(huán)境，普通頁面中為wx，自定義組件中為this；默認值為wx.
 * @return {Array} 返回一個數(shù)組，第一個元素為 node 節(jié)點
 */
export const querySelector = function (selector, context = wx) {
 return new Promise((resolve, reject) => {
 context.createSelectorQuery()
 .select(selector)
 .boundingClientRect((res) => {
  if (res) {
  resolve(res);
  } else {
  reject(`不存在選擇器為 ${selector} 的節(jié)點`);
  }
 })
 .exec();
 })
};

 <waterfall
  loading="{{loadMorePending}}"
  isAllLoaded="{{isAllLoaded}}"
 >
  <block wx:for="{{data.sections}}" wx:key="id" wx:for-item="product">
  <waterfall-item
   index="{{index}}"
   custom-class="flow-item-wrapper"
  >
   <view class="product-item">
   業(yè)務(wù)代碼
   </view>
  </waterfall-item>
  </block>
 </waterfall>

// waterfall-item.js
import { querySelector } from './query-node';
Component({
 // ... other code
 lifetimes: {
 ready() {
  const [waterfall] = this.getRelationNodes('./waterfall');
  this.parent = waterfall;
  this.setWaterfallItemPosition();
 },
 }
 methods:{
 async setWaterfallItemPosition() {
  querySelector('.waterfall-item', this)
  .then(async (node) => {
   const { top, position } = await this.parent.getWaterfallItemPostionInfo(node);
   this.setData({
   top,
   position
   })
  })
 }, 
 }
 // ... other code
})

// waterfall.js
const POSITION_LEFT = 'left';
const POSITION_RIGHT = 'right';

Component({
 // ... other code
 /**
 * 組件的方法列表
 */
 methods: {
 lifetimes: {
  ready() {
  this.initParams();
  }
  },
 initParams() {
  this.leftHeights = 0;
  this.rightHeights = 0;
 },
 /**
  * 設(shè)置 waterfall-item 的高度值
  * @param {Object} node waterfall-item 組件位置尺寸數(shù)據(jù)
  */
 async getWaterfallItemPostionInfo(node) {
  let top = 0;
  let position = POSITION_LEFT;
  const { height } = node;
  const { itemGap } = this;
  if (this.leftHeights <= this.rightHeights) {
  top = this.leftHeights;
  if(this.leftHeights === 0) {
   this.leftHeights += height;
  } else {
   top += itemGap;
   this.leftHeights += (height + itemGap);
  }
  } else {
  position = POSITION_RIGHT;
  top = this.rightHeights;
  if(this.rightHeights === 0) {
   this.rightHeights += height;
  } else {
   top += itemGap;
   this.rightHeights += (height + itemGap);
  }
  }
  return {
  top,
  position,
  }
 }
 // ... other code
 }
})

<view
 class="waterfall-item custom-class"
 style="{{position}}:0;top:{{(top >= 0 ? top + 'px' : itemCount * 100 + 'vh')}};"
>
 <slot ></slot>
</view>

Component({
 // waterfall-item.js
 // ... other code
 lifetimes: {
 ready() {
  const { itemCount } = this.data;
  const [waterfall] = this.getRelationNodes('./waterfall');
  waterfall.childCount += 1;
  this.parent = waterfall;
  this.setData({
  itemCount: itemCount + waterfall.childCount,
  })
 },
 },
 // ... other code
})

itemGap = waterfall寬度 - （waterfall-item寬度 * 2）

// this.leftHeights += height + itemGap;
// or 
// this.rightHeights += height + itemGap;