javascript当中options的用法
6.options
马克-to-win：选择列表
例 6.1（SelectOptionAddIEFF.html）
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8"/>
<TITLE>
</TITLE>
<SCRIPT LANGUAGE="JavaScript">
<!--
/* a typical value is that document.getElementById("province").options[1]="河北", document.getElementById("city").options[1]= arr[0][1]= "石家庄" */
var arr = new Array(
new Array("河北", "邯郸","石家庄"),
new Array("山东", "济南", "枣庄", "威海"),
new Array("河南", "开封", "郑州", "洛阳", "南洋")
);
function setProvinces()
{
/* arr.length is the row number of arr, arr[i][0] the first column. in other words, 河北,山东,河南 */
for (var i = 0; i < arr.length; i++)
{ /*加到option最后,new Option(str1,str2)str1 是页面中看到的描述,而str2是这一项的值*/
document.getElementById("province").options[i + 1] = new Option(arr[i][0], arr[i][0]);
}
}
function setCity(i)
{ alert(i+" "+document.getElementById("province").selectedIndex+document.getElementById("province").value+document.getElementById("province").options[document.getElementById("province").selectedIndex].text+document.getElementById("province").options[document.getElementById("province").selectedIndex].value);
document.getElementById("city").options.length = 1;//reset city
for (var j = 1; j < arr[i - 1].length; j++)
{
opt = new Option(arr[i - 1][j], arr[i - 1][j]);
/*下面两种写法的结果是一样的*/
// document.getElementById("city").options[j] = new Option(arr[i - 1][j], arr[i - 1][j]);
document.getElementById("city").add(opt,document.getElementById("city").options.length);//第二个参数指定元素放置所在的索引号
}
// objSelect.add(objOption, objSelect.selectedIndex);
}
//-->
</SCRIPT>
</HEAD>
<BODY οnlοad="setProvinces()">
<!--Select.selectedIndex (Property)
qixy: through experiment: Select.selectedIndex is 0-based.但是第0项是“请选择省份-- ”
-->
<select name="select" id="province" οnchange="setCity(this.selectedIndex);">
<option value="0">请选择省份--</option>
</select>
<select name="select2" id="city">
<option value="0">请选择城市--</option>
</select>
</BODY>
</HTML>
更多内容请见原文，文章转载自：https://blog.csdn.net/qq_43650923/article/details/102467341
