滚定区域内，把子元素滚动到 父元素中间位置(如：可滚动横向 tab 滚动到中间位置)

[JslinSir]

// parentEl代表父元素，也就是设置了overflow为可滚动的元素
    // childEl代表需要滚动到父元素正中间的直接子元素

    // 水平滚动
    let x = childEl.offsetLeft - parentEl.clientWidth + parentEl.clientWidth/2 + childEl.clientWidth/2;
    parentEl.scrollTo({
        left: x,
        behavior: "smooth",
    });

    // 垂直滚动
    let y = childEl.offsetTop - parentEl.clientHeight + parentEl.clientHeight/2 + childEl.clientHeight/2;
    parentEl.scrollTo({
        top: y,
        behavior: "smooth",
    });

[JslinSir]

// 小程序中使用示例
  async handleSelectTab(event){
      const { selectIndex } = this.data
     const { index } = event.currentTarget.dataset
     if(selectIndex!=index){
       const parentEl = await this.getNodeRef('.brand-cate-scroll',true)
       const childElAll = await this.getNodeRef(`.brand-cate-item`,true,'selectAll')
       const childEl = childElAll[index]
       const scrollX = childEl.left - parentEl.width + parentEl.width/2 + childEl.width/2;
       this.setData({ selectIndex:index,scrollX })
     }
    },

 
    getNodeRef(select,memo=false,selectType='select') {
      return new Promise((revose) => {
        if(memo && this[`_${select}_Rect`]){
          revose(this[`_${select}_Rect`]);
          return
        }
        const query = this.createSelectorQuery();
        query[selectType](select).boundingClientRect();
        query.exec((res) => {
          this[`_${select}_Rect`] = res[0]
          revose(res[0]);
        });
      });
    },