原生JavaScript 瀑布流 實現 zx-waterfall

源碼地址： https://github.com/capricornc...

使用說明

Install zx-waterfall using npm

npm i --save zx-waterfall

ES6+

import ZxWaterfall from 'zx-waterfall'

const waterfall = new ZxWaterfall({
  // HTMLElement, waterfall items's outer container
  container: document.getElementById('zxWaterfall'),
  // children item selector, eg. '.item-container'
  itemSelector: '.item-wrapper',
  // item's spacing, unit px
  gutter: 20,
  // item's width
  itemWidth: 300
})
// reset
waterfall.reset()
// loaMedias
waterfall.loadMedia(['http://xx.com/aaa.jpg']).then(_ => {
  // change
  waterfall.change()
})

browser

<script src="path/zx-waterfall.min.js"></script>

demo

https://capricorncd.github.io...

注意

• container 's style must be style.position=relative|absolute|fixed

參數options

• container: HTMLElement

  瀑布流外容器.

• containerWidth: Number

  瀑布流寬度，若是初始化時外容器未隱藏狀態則需使用該參數.

  默認獲取外容器寬度.

• itemSelector: String

  子元素選擇器，好比 樣式名'.item-container'.

• gutter: Number

  元素間的間隔.

• verticalGutter: Number

  元素間垂直方向間隔，默認使用gutter值.

• itemWidth: Number

  元素寬度, 默認 300, 會根據容器寬度自動調整.

• forceItemWidth: Boolean

  強制元素寬度，即便用itemWidth做爲寬度值，默認 false.

• align: String, Optional value left|center|right

  強制寬度時，元素顯示靠邊位置，默認 center.

方法

• reset()

  重置瀑布流初始值

• loadMeida(array)

  預加載列表數據中的image媒體元素.

  array: ['http://a.com/1.jpg', 'http://a.com/2.jpg']

  @return promise

• change()

  列表數據改變後後，通知瀑布流更新元素位置.

源碼

/**
 * preload image
 * @param url
 * @param handler
 */
function loadImage (url, handler) {
  let $el = document.createElement('img')
  $el.src = url
  $el.onload = handler
  $el.onerror = handler
  $el = null
}

/**
 * to int
 * @param m
 * @returns {number}
 */
function int (m) {
  let n = parseInt(m)
  return isNaN(n) ? 0 : n
}

/**
 * convert pseudoArray to array
 * @param pseudoArray
 * @param index
 * @returns {T[]}
 */
function slice (pseudoArray, index) {
  return Array.prototype.slice.call(pseudoArray, int(index))
}

// default options
const DEF_OPTIONS = {
  // HTMLElement, waterfall items's outer container
  container: null,
  // container's width, container are hidden when initialized
  // default get container offsetWidth when it's visible
  containerWidth: 0,
  // children item selector, eg. '.item-container'
  itemSelector: '',
  // item's spacing, unit px
  gutter: 20,
  // item's vertical spacing, default use gutter's value
  verticalGutter: 0,
  // item's width
  itemWidth: 300,
  // force item width
  forceItemWidth: false,
  // Horizontal align when forceItemWidth is true
  align: 'center'
}

/**
 * ZxWaterfall
 */
class ZxWaterfall {
  /**
   * constructor
   * @param opts
   */
  constructor (opts) {
    opts = Object.assign({}, DEF_OPTIONS, opts)
    // check container
    if (!opts.container || opts.container.nodeType !== 1) {
      throw new TypeError(`Instancing parameter 'container' is not HTMLElement.`)
    }
    // check itemSelector
    if (!opts.itemSelector || typeof opts.itemSelector !== 'string') {
      throw new TypeError(`Instancing parameter 'itemSelector' is null or is't a string.`)
    }
    // check verticalGutter
    if (!opts.verticalGutter) {
      opts.verticalGutter = opts.gutter
    }
    // item number
    this.count = 0
    this.opts = opts
    this._init()
    // clone this.reset
    this._resetClone = this.reset.bind(this)
    window.addEventListener('resize', this._resetClone)
  }

  /**
   * initialization
   * @private
   */
  _init () {
    let opts = this.opts
    // container width
    let containerWidth = int(opts.containerWidth) || opts.container.offsetWidth
    // column number
    let columnNum = Math.floor(containerWidth / (opts.itemWidth + opts.gutter))
    // opts.itemWidth when opts.forceItemWidth = true
    // else use compute new width
    this.itemWidth = opts.forceItemWidth
      ? opts.itemWidth
      : (containerWidth - (columnNum + 1) * opts.gutter) / columnNum
    // column current height array
    this.columns = Array(columnNum)
    this.columns.fill(0, 0)
    // offset left when forceItemWidth=true
    this.offsetLeft = 0
    if (opts.forceItemWidth) {
      let residualSpaceWidth = containerWidth - (this.itemWidth + opts.gutter) * columnNum - opts.gutter
      switch (opts.align) {
        case 'center':
          this.offsetLeft = residualSpaceWidth / 2
          break
        case 'right':
          this.offsetLeft = residualSpaceWidth
          break
      }
    }
  }

  /**
   * set items position
   * @private
   */
  _setPosition () {
    let opts = this.opts
    // get new item elements
    let $childs = slice(opts.container.querySelectorAll(opts.itemSelector), this.count)
    // console.log(this.count, $childs)
    let len = $childs.length
    // reset this.count value
    this.count += len
    // handle new $item
    let i, $item
    for (i = 0; i < len; i++) {
      $item = $childs[i]
      if (!$item) continue
      $item.style.position = 'absolute'
      $item.style.width = this.itemWidth + 'px'
      $item.style.display = 'inline-block'
      // get columns min value
      let min = Math.min.apply(null, this.columns)
      let index = this.columns.findIndex(val => val === min)
      // set $item position
      $item.style.top = `${min + opts.verticalGutter}px`
      $item.style.left = `${this.offsetLeft + (this.itemWidth + opts.gutter) * index + opts.gutter}px`
      // reset waterfall current column height value
      let itemHeight = $item.offsetHeight
      this.columns[index] = min + itemHeight + opts.verticalGutter
      // update container new min height style
      // opts.container.style.minHeight = Math.max.apply(null, this.columns) + opts.verticalGutter + 'px'
    }
  }

  /**
   * container's items number change
   */
  change () {
    // reset postion, when new item element append to container, or remove
    this._setPosition()
  }

  /**
   * reset
   */
  reset () {
    this.count = 0
    this._init()
    this._setPosition()
  }

  /**
   * preload media items
   * @param arr media source urls array
   * @returns {Promise<any>}
   */
  loadMedia (arr) {
    return new Promise(resolve => {
      if (Array.isArray(arr) && arr.length) {
        let len = arr.length
        let count = 0
        /* eslint-disable */
        arr.forEach(url => {
          loadImage(url, () => {
            count++
            if (len === count) resolve()
          })
        })
      } else {
        resolve()
      }
    })
  }

  /**
   * destroy
   * removeEventListener window resize
   */
  destroy () {
    window.removeEventListener('resize', this._resetClone)
  }
}

export default ZxWaterfall

demo: https://github.com/capricornc...