1.三个按钮,点击任意按钮所有的按钮本景色改变
<body>
<input type="button" value="按钮1">
<input type="button" value="按钮2">
<input type="button" value="按钮3">
<script>
var buttons = document.getElementsByTagName("input")
for(var i = 0; i< buttons.length; i++){
buttons[i].onclick = function(){
for(var j = 0; j < buttons.length; j++){
buttons[j].style.background = 'yellow';
}
}
}
</script>