正则表达式判断手机号是否11位

<script src="../JS/jquery-3.2.0.js" type="text/javascript" ></script>
<script src="../JS/bootstrap.min.js"></script>
<link type="text/css" rel="stylesheet" href="../css/bootstrap.min.css" />

<body>
<div class="form-group">
            	<label class="col-sm-2 control-label font">手机号</label>
        			<div class="col-sm-10 ">
            			<input type="text" class="form-control bt" name="tel" ></span>
        			</div>
        	</div><br/><br/><br/>
</body>

<script>
function checkMobile(str) {
     
    var  re = /^1\d{10}$/
    if (re.test(str)) {
		  $("#sj").html("手机号码格式正确");
		  $("#sj").css("color","green"); 
    } 
	else {
          $("#sj").html("手机号码格式错误");
		  $("#sj").css("color","red"); 
    }
}
$("#tel").blur(function(){
		var str = $(this).val();
		checkMobile(str);
})
</script>