javascript动态添加下载框及选项

javascript动态添加下载框及选项

内容来源:

https://blog.csdn.net/qq_21703215/article/details/58599911
http://www.jb51.net/article/35205.htm

动态创建select

function createSelect(){
var mySelect = document.createElement("select");
mySelect.id = "mySelect";
document.body.appendChild(mySelect);
}

添加选项option

function addOption(){
//根据id查找对象,
var obj=document.getElementById('mySelect');
//添加一个选项
obj.add(new Option("文本","值")); //这个只能在IE中有效
obj.options.add(new Option("text","value")); //这个兼容IE与firefox
}

删除所有选项option

function removeAll(){
var obj=document.getElementById('mySelect');
obj.options.length=0;
}

删除一个选项option

function removeOne(){
var obj=document.getElementById('mySelect');
//index,要删除选项的序号,这里取当前选中选项的序号
var index=obj.selectedIndex;
obj.options.remove(index);
}

获得选项option的值

var obj=document.getElementById('mySelect'); 
var index=obj.selectedIndex; //序号,取当前选中选项的序号 
var val = obj.options[index].value; 

获得选项option的文本

var obj=document.getElementById('mySelect'); 
var index=obj.selectedIndex; //序号,取当前选中选项的序号 
var val = obj.options[index].text;

修改选项option

var obj=document.getElementById('mySelect'); 
var index=obj.selectedIndex; //序号,取当前选中选项的序号 
var val = obj.options[index]=new Option("新文本","新值"); 

删除select

function removeSelect(){ 
var mySelect = document.getElementById("mySelect"); 
mySelect.parentNode.removeChild(mySelect); 
} 

完整代码如下

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//ZH-CN" "http://www.w3.org/TR/html4/strict.dtd"> 
<html> 
<head> 
<meta http-equiv="Content-Type" content="text/html"> 
<head> 
<script language=JavaScript> 
function $(id) 
{ 
return document.getElementById(id) 
} 
function show() 
{ 
var selectObj=$("area") 
var myOption=document.createElement("option") 
myOption.setAttribute("value","10") 
myOption.appendChild(document.createTextNode("上海")) 
var myOption1=document.createElement("option") 
myOption1.setAttribute("value","100") 
myOption1.appendChild(document.createTextNode("南京")) 
selectObj.appendChild(myOption) 
selectObj.appendChild(myOption1) 
} 
function choice() 
{ 
var index=$("area").selectedIndex; 
var val=$("area").options[index].getAttribute("value") 
if(val==10) 
{ 
var i=$("context").childNodes.length-1; 
var remobj=$("context").childNodes[i]; 
remobj.removeNode(true) 
var sh=document.createElement("select") 
sh.add(new Option("浦东新区","101")) 
sh.add(new Option("黄浦区","102")) 
sh.add(new Option("徐汇区","103")) 
sh.add(new Option("普陀区","104")) 
$("context").appendChild(sh) 
} 
if(val==100) 
{ 
var i=$("context").childNodes.length-1; 
var remobj=$("context").childNodes[i]; 
remobj.removeNode(true) 
var nj=document.createElement("select") 
nj.add(new Option("玄武区","201")) 
nj.add(new Option("白下区","202")) 
nj.add(new Option("下关区","203")) 
nj.add(new Option("栖霞区","204")) 
$("context").appendChild(nj) 
} 
} 
function calc() 
{ 
var x=$("context").childNodes.length-1; 
alert(x) 
} 
function remove() 
{ 
var i=$("context").childNodes.length-1; 
var remobj=$("context").childNodes[i]; 
remobj.removeNode(true) 
} 
</script> 
<body> 
<div id="context"> 
<select id="area" onchange="choice()"> 
</select> 
</div> 
<input type=button value="显示" onclick="show()"> 
<input type=button value="计算结点" onclick="calc()"> 
<input type=button value="删除" onclick="remove()"> 
</body> 
</html>

改进版:在select中添加、修改、删除option元素

function watch_ini(){ // 初始 
for(var i=0; i<arguments.length; i++){ 
var word = document.createElement("OPTION"); 
word.text = arguments[i]; 
watch.keywords.add(word); // watch. is form name 
} 
} 
function watch_add(f){ // 增加 
var word = document.createElement("OPTION"); 
word.text = f.word.value; 
f.keywords.add(word); 
}

兼容FF和Opera,对上述代码进行了一下改进,改动后代码如下:

function watch_ini(){ // 初始 
for(var i=0; i<arguments.length; i++){ 
var oOption=new Option(arguments[i],arguments[i]); 
document.getElementById("MySelect")[i]=oOption; 
} 
} 
function watch_add(f){ // 增加 
var oOption=new Option(f.word.value,f.word.value); 
f.keywords[f.keywords.length]=oOption; 
}

整个实例的完整代码如下

<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> 
<html> 
<head> 
<title>javascript select options text value</title> 
<meta name="keywords" content="javascript select options text value add modify delete set"> 
<meta name="description" content="javascript select options text value add modify delete set"> 
<script language="javascript"> 
<!-- 
function watch_ini(){ // 初始 
for(var i=0; i<arguments.length; i++){ 
var oOption=new Option(arguments[i],arguments[i]); 
document.getElementById("MySelect")[i]=oOption; 
} 
} 
function watch_add(f){ // 增加 
var oOption=new Option(f.word.value,f.word.value); 
f.keywords[f.keywords.length]=oOption; 
} 
function watch_sel(f){ // 编辑 
f.word.value = f.keywords[f.keywords.selectedIndex].text; 
} 
function watch_mod(f){ // 修改 
f.keywords[f.keywords.selectedIndex].text = f.word.value; 
} 
function watch_del(f){ // 删除 
f.keywords.remove(f.keywords.selectedIndex); 
} 
function watch_set(f){ // 保存 
var set = ""; 
for(var i=0; i<f.keywords.length; i++){ 
set += f.keywords[i].text + ";"; 
} 
confirm(set); 
} 
//--> 
</script> 
</head> 
<body> 
<form name="watch" method="post" action=""> 
<select id="MySelect" name="keywords" size="10" onchange="watch_sel(this.form)"></select><br> 
<script language="javascript"> 
<!-- 
watch_ini("我","你","妳","他","她","它","尔"); // 初始关键词 
//--> 
</script> 
<input type="text" name="word" /><br /> 
<input type="button" value="增加" onclick="watch_add(this.form);" /> 
<input type="button" value="修改" onclick="watch_mod(this.form);" /> 
<input type="button" value="删除" onclick="watch_del(this.form);" /> 
<input type="button" value="保存" onclick="watch_set(this.form);" /> 
</form>

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