FrankFan/setColor

## setColor
<html>
<head>
	<title>Javascript quiz</title>
	<meta charset="utf-8">
	<script type="text/javascript">
		/*
 		 * 要求：
 		 * how to use js to set the backgournd color of the
 		 * sencond option(value="b") to be grey?
		 */
		 function setColor () {
		 	var option = document.getElementsByTagName("option");
		 	option[1].style.backgroundColor = "gray";
		 }
	</script>
</head>
<body>
	<div>
		<select>
			<option value="a">Hello</option>
			<option value="b">World</option>
		</select>
		<input type="button" value="set color" onclick="setColor()">
	</div>

</body>
</html>
	<html>
	<head>
	<title>Javascript quiz</title>
	<meta charset="utf-8">
	<script type="text/javascript">
	/*
	* 要求：
	* how to use js to set the backgournd color of the
	* sencond option(value="b") to be grey?
	*/
	function setColor () {
	var option = document.getElementsByTagName("option");
	option[1].style.backgroundColor = "gray";
	}
	</script>
	</head>
	<body>
	<div>
	<select>
	<option value="a">Hello</option>
	<option value="b">World</option>
	</select>
	<input type="button" value="set color" onclick="setColor()">
	</div>

	</body>
	</html>