select选中事件用change，（用click会执行两次）；
select标签对移动端的兼容：
.custom-selectselect{
width:100%; margin:0;
background:none;
border:1px solid transparent;
outline: none;/* Prefixed box-sizing rules necessary for older browsers */
-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
box-sizing: border-box;/* Remove select styling */ appearance: none;
-webkit-appearance: none;/* Font size must the 16px or larger to prevent iOS page zoom on focus *//* General select styles: change as needed */
font-family: helvetica, sans-serif;
font-weight: bold;
color:#444;
padding:.6em1.9em.5em.8em;
line-height:1.3;}
.custom-select::after{
content:"";
position: absolute;
width:0px;
height:0px;
top:50%;
right:8px;
margin-top:-4px;
border:8px solid #929497;
border-width:8px5px8px;
border-color:#929497 transparent transparent transparent;
z-index:2;
pointer-events:none;
}