uni-app获取元素宽高封装

getElSize(id) { //得到元素的size
    return new Promise((res, rej) => {
          uni.createSelectorQuery().select('#' + id).fields({
               size: true,
               scrollOffset: true
           }, (data) => {
                  res(data);
           }).exec();
    });
},

// 异步调用

async tapTab(index) { //点击tab-bar
	if (this.tabIndex === index) {
		return false;
	} else {
		let tabBar = await this.getElSize("tab-bar"),
		console.log(tabBar) 
} },