第一题：完成省城市的三级联动（包括湖南省），附代码和效果图。
<!DOCTYPE HTML>
<html>
<head>
</head>
<body>
<select id="province">
<option value="-1">请选择</option>
</select>
<select id="city"></select>
<select id="country"></select>
<script type="text/javascript">
var provinceArr = ['上海','江苏','河北'];
var cityArr = [
['上海市'],
['苏州市','南京市','扬州市'],
['石家庄','秦皇岛','张家口']
];
var countryArr = [
[
['黄浦区','静安区','长宁区','浦东区']
],
[
['虎丘区','吴中区','相城区','姑苏区','吴江区'],['玄武区','秦淮区','建邺区','鼓楼区','浦口区'],['邗江区 ','广陵区','江都区']
],
[
['长安区','桥西区','新华区','井刭矿区'],['海港区','山海关区','北戴河区','抚宁区'],['桥东区','桥西区','宣化区','下花园区']
]
];
function createOption(obj,data){
for(var i in data){
var op = new Option(data[i],i);
obj.options.add(op);
}
}
var province = document.getElementById('province');
createOption(province,provinceArr);
var city = document.getElementById('city');
province.onchange = function(){
city.options.length = 0;
createOption(city,cityArr[province.value]);
};
var country = document.getElementById('country');
city.onchange = function(){
country.options.length = 0;
createOption(country,countryArr[province.value][city.value]);
};
province.onchange = function(){
city.options.length = 0;
createOption(city,cityArr[province.value]);
if(province.value>=0){
city.onchange();
}
else{
country.options.length = 0;
}
};
</script>
</body>
</html>
第二题：移出数组arr([1,2,3,4,2,5,6,2,7,2])中与2相等的元素，并生成一个新数组,不改变原数组。
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<script>
var arr = [1,2,3,4,2,5,6,2,7,2];
document.write("原数组：<br/>" + arr);
var a= arr.slice(3,4);
var b = arr.slice(0,1);
var c = arr.slice(2,3);
var d = arr.slice(5,6);
var e = arr.slice(6,7);
var f = arr.slice(8,9);
str = b.concat(c,a,d,e,f);
document.write("<br/>");
document.write("新数组：<br/>" + str);
document.write("<br/>");
document.write("原数组arr：<br/>" + arr);
</script>
</body>
</html>
第三题：编写函数实现单击change按钮，为div元素添加红色双线的边框。
<html>
<head>
<meta charset="utf-8">
<style type="text/css">
div{
font-family: "Helvetica Neue",Helvetica,Arial,"Microsoft Yahei",sans-serif;
width: 600px;
text-align: center;
}
.haha{
margin-top: 20px;
margin-left: 250px;
font-size: 20px;
}
.haha:hover{
border: 3px solid purple;
}
</style>
</head>
<body>
<div id="joy">
<p>做自己想做的事</p>
</div>
<button class="haha" onclick="myFunction()">change</button>
<script type="text/javascript">
function myFunction(){
var Color = document.getElementById("joy");
Color.style.border = "3px double red";
Color.innerHTML = "<p>加油！</p>";
}
</script>
</body>
</html>