MUI中頁面返回，鍵盤不消失，而是直接返回到上級頁面，鍵盤依然存在

<!--點擊返回先退出鍵盤-->
<div class="search pd-10">
	<input id="lowInsurance" class="mgb-0" type="text" placeholder="請輸入查詢人身份證號" />
	<span class="mui-icon iconfont icon-chazhao f-20 color-gray fdj" id="start"></span>
</div>

<script type="text/javascript">
	var isShow = false;
	var inputElm = document.getElementById('lowInsurance');
	inputElm.addEventListener('focus', function() {
		isShow = true;
	})
	inputElm.addEventListener('blur', function() {
		isShow = false;
	})

	var _back = mui.back;
	mui.back = function() {
		if(isShow) {
			inputElm.blur();
		} else {
			_back();
		}
	}
</script>