計算表格位置的程式碼

offset.js

  offsetBody () {
    const scrollTop = (this.$refs.viewport as Element).scrollTop
    const remainTopNumber = Math.floor(this.remainLineNumber / 2)
    const remainTopHeight = remainTopNumber * this.renderLineHeight
    const remainBottomHeight = (this.remainLineNumber - remainTopNumber) * this.renderLineHeight
    const thresholdHeight = this.thresholdNumber * this.renderLineHeight
    const gap = scrollTop - this.bodyTranslateY
    const overThreshold = gap < remainTopHeight - thresholdHeight || gap > remainTopHeight + thresholdHeight
    const isReachBottom = this.totalHeight - (scrollTop + this.viewportHeight) < remainBottomHeight
    const isReachTop = scrollTop < remainTopHeight
    if (isReachTop) {
      this.offset = 0
      this.bodyTranslateY = 0
    } else if (isReachBottom) {
      this.offset = this.items.length - this.renderLineNumber
      this.bodyTranslateY = this.totalHeight - this.renderBodyHeight
    } else if (overThreshold) {
      this.offset = Math.floor(scrollTop / this.renderLineHeight) - remainTopNumber
      this.bodyTranslateY = scrollTop - remainTopHeight
    }
  }