<script type="text/javascript">

var getRandomColor = function(){

    return (function(m,s,c){

    return (c ? arguments.callee(m,s,c-1) : '#') +

      s[m.floor(m.random() * 16)]

    })(Math,'0123456789abcdef',5)

}

var btnArr = document.getElementsByTagName("button");

var main = document.getElementById("main");

for (var i = 0; i < btnArr.length; i++) {

btnArr[i].onclick = function() {

for (var i = 0; i < btnArr.length; i++) {

btnArr[i].style.backgroundColor = "darkgray";

}

this.style.backgroundColor = "#FF0000";

main.innerHTML = "第" + this.innerHTML + "个盒子";

main.style.backgroundColor = getRandomColor();

}

}

</script>