SOURCE

const waterfallify = (heightList, columnCount, setPositionCallback) => {
	const result = []
	const totalHeightArr = new Array(columnCount).fill(0)
	heightList.forEach( (heightItem, index) => {
		const minIndex = getMin(totalHeightArr).index

		if(result[minIndex]) {
			result[minIndex].push(index)
		}else {
			result[minIndex] = [index]
		}
		
		totalHeightArr[minIndex] += heightItem

		setPositionCallback && setPositionCallback(index, minIndex)
	})
	return result
}

const getMin = (arr) => {
	let min = Number.POSITIVE_INFINITY
	let minIndex = -1
	arr.forEach((item, index) => {
		if(item < min) {
			min = item
			minIndex = index
		} 
	})
	return {
		index: minIndex,
		number: min
	}
}










const imagelist=[
  {src:'',prview_height:228},
  {src:'',prview_height:345},
  {src:'',prview_height:124},
  {src:'',prview_height:300},
  {src:'',prview_height:400},
  {src:'',prview_height:200},
  {src:'',prview_height:209}
]

const list = imagelist.map(image => image.prview_height)

let result = waterfallify(list,2,(index,index2) =>{})
result = result.map(resultItem => {
  return resultItem.map(item => {
  	return imagelist[item]
  })
})

document.write('<hr>')

document.write(result.map((item,index) => `第${index}列：${item}`).join('<br>'))