                        课程
                    
                        /前端开发
                        
                            /JavaScript
                        
                        /JavaScript进阶篇

想知道哪里错了....

<body>
<label>请输入北京今天空气质量：<input id="aqi-input" type="text"></label>
<button id="button">确认填写</button>
<div>您输入的值是：<span id="aqi-display">尚无录入</span></div>
<script type="text/javascript">

var btn=document.getElementById("button");
var input = document.getElementById("aqi-input");
var display = document.getElementById("aqi-display");
btn.onclick = function(){
    if (input.value != none) {
      display.innerHTML = input.value;
    }
    else {
      alert("请输入北京今天空气质量");
    }
}

</script>
</body>