前端：点击底部导航切换图标文字

H5点击底部导航切换图标文字

html代码：

<div class="btm_group">
        <div class="bbtn btn1 btm_s" data-type="u" data-id="1" >
            <img id="b_img1" src="__PUBLIC__/img/btm1-s.png" class=""/>
            <span>福利</span>
        </div>
        <div class="bbtn btn2" data-type="u" data-id="2" >
            <img id="b_img2" src="__PUBLIC__/img/btm2-u.png" class=""/>
            <span>书城</span>
        </div>
        <div class="bbtn btn3" data-type="u" data-id="3" >
            <img id="b_img3" src="__PUBLIC__/img/btm3-u.png" class=""/>
            <span>我的</span>
        </div>
    &