JavaScript点击图片完成开关灯操作

<img src="https://ts1.cn.mm.bing.net/th?id=OIP-C.uRmt28CEJJzgrVHrQT8f2AHaKL&w=100&h=137&c=8&rs=1&qlt=90&o=6&dpr=1.25&pid=3.1&rm=2" id="and">
<script>
    var flag=false;
    var and=document.getElementById("and")
    and.onclick=function(){
        if(flag){
            and.src="https://ts1.cn.mm.bing.net/th?id=OIP-C.uRmt28CEJJzgrVHrQT8f2AHaKL&w=100&h=137&c=8&rs=1&qlt=90&o=6&dpr=1.25&pid=3.1&rm=2"
            flag=false
        }else{
            and.src="https://ts1.cn.mm.bing.net/th?id=OIP-C.rSvX87qpmdduRDE5V6lxfAHaHb&w=138&h=137&c=8&rs=1&qlt=90&o=6&dpr=1.25&pid=3.1&rm=2"
            flag=true
        }
    }
</script>