????：<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width,&
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style media="screen">
.center{padding-top: 20px;text-align: center;}
input{width: 50px;height: 25px;background: rgb(0,0,0,0);}
#box{width: 100px;height: 100px;background:#2E6CD6;margin: 0 auto;margin-top: 50px;}
</style>
</head>
<body>
<div>
<input type="button" value="變寬" onclick="Owidth()"> <!-- 當(dāng)用戶點(diǎn)擊按鈕觸發(fā)事件函數(shù) -->
<input type="button" value="變高" onclick="Oheight()">
<input type="button" value="變色" onclick="Obgcolor()">
<input type="button" value="變圓" onclick="Oradius()">
<input type="button" value="隱身" onclick="Onone()">
<input type="button" value="顯示" onclick="Oblock()">
<input type="button" value="重置" onclick="Orest()">
<div id="box"></div>
</div>
<script type="text/javascript">
var box;
window.onload = function (){ //window.onload 事件加載完后觸發(fā)，這應(yīng)該算是為全局函數(shù)了吧！
box = document.getElementById('box');//獲取頁面中的 DOM元素
}
function Owidth(){ //聲明一個(gè)函數(shù)名 Owidth ，然后通過全局函數(shù)獲取到的DOM元素修改其CSS樣式
box.style.width = "400px"//請(qǐng)教下老師，“400px”后面要加分號(hào)嗎？加到“”里面結(jié)果效果出不來。
}
function Oheight(){
box.style.height = "400px"
}
function Obgcolor(){
box.style.background = "#AD05FF"
}
function Oradius(){
box.style.borderRadius = "50%"
}
function Onone(){
box.style.display = "none"
}
function Oblock(){
box.style.display = "block"
}
function Orest(){//重置
box.style.width = "100px"
box.style.height = "100px"
box.style.background = "#2E6CD6"
box.style.borderRadius = "0"
}
</script>
</body>
</html>老師看下我注釋中的理解是否有誤，請(qǐng)您指點(diǎn)，辛苦了您！
?? ???：天蓬老師?? ??：2018-11-25 20:21:43
???? ??：如果用window.onload , 那么js代碼可以放到head中,不必放到body前了,注釋還算清楚,畢竟初學(xué),離規(guī)范還有差距.
還有,注釋盡可能寫到語句上面,不要寫到右邊,便于進(jìn)行調(diào)試