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About CSS Base

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JavaScript preprocessors can help make authoring JavaScript easier and more convenient. For instance, CoffeeScript can help prevent easy-to-make mistakes and offer a cleaner syntax and Babel can bring ECMAScript 6 features to browsers that only support ECMAScript 5.

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HTML

            
              div#head.box
div.box
div.box
div.box
div.box
div.box
div.box
!

CSS

            
              colors = red orange yellow green cyan blue purple

reverse(i)
  100 - i

.box
  position absolute
  transform translate(10px, 10px)
  transition 0.1s transform ease-out
  width 40px
  height 40px
  background orange
  cursor pointer

  for color, i in colors
    &:nth-child({i + 1})
      background color
      z-index reverse(i)
      if color != red
        pointer-events: none
!

JS

            
              const headBox = document.getElementById('head')
const boxes = document.getElementsByClassName('box')
const mouseDown$ = Rx.Observable.fromEvent(headBox, 'mousedown')
const mouseMove$ = Rx.Observable.fromEvent(document, 'mousemove')
const mouseUp$ = Rx.Observable.fromEvent(document, 'mouseup')
const delayBoxes$ = Rx.Observable.from([].slice.call(boxes, 0))
  .zip(Rx.Observable.interval(100).startWith(0), (box) => box)

mouseDown$.map((e) => {
  const pos = getTranslate(headBox)
  return {
    pos,
    event: e,
  }
})
.switchMap((initialState) => {
  const initialPos = initialState.pos
  const { clientX, clientY } = initialState.event
  return mouseMove$.map((moveEvent) => ({
    x: moveEvent.clientX - clientX + initialPos.x,
    y: moveEvent.clientY - clientY + initialPos.y,
  }))
  .takeUntil(mouseUp$)
})
.mergeMap((pos) => {
  return delayBoxes$.do((box) => {
    setTranslate(box, pos)
  })
})
.subscribe()

function getTranslate (element) {
  const style = getComputedStyle(element)
  const regExp = /matrix\((\d+,\s){4}(\d+),\s(\d+)/i
  const result = style.transform.match(regExp)
  if (result) {
    return {
      x: parseInt(result[2], 10),
      y: parseInt(result[3], 10)
    }
  } else {
    return {
      x: 0,
      y: 0
    }
  }
}

function setTranslate (element, pos) {
  element.style.transform = `translate(${pos.x}px, ${pos.y}px)`
}
!
999px
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