<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<img src="img/foot4.png" alt="pic"/>
<button id="btn">开关</button>
<script type="text/javascript">
(function(){
var img=document.getElementsByTagName("img")[0];
var flag=true;
document.getElementById("btn").onclick=function(){
if(flag){
img.style.visibility="hidden";
}else{
img.style.visibility="visible";
}
flag=!flag;
}
})();
</script>
</body>
</html>
================================================================================================
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<select name="type">
<option value="0">请选择品牌</option>
<option value="bmw">宝马</option>
<option value="bc">奔驰</option>
</select>
<select name="pro">
<option value="">-----</option>
</select>
<script type="text/javascript">
(function(){
var array=new Array();
array["bmw"]=["b1","b2","b3"];
array["bc"]=["bc1","bc2"];
document.getElementsByName("type")[0].onchange=function(){
var v=this.value;
document.getElementsByName("pro")[0].options.length=1;
for(var index in array[v]){
var value=array[v][index];
var option=new Option(value,value);
document.getElementsByName("pro")[0].add(option);
}
}
})();
</script>
</body>
</html>
================================================================================================