方法有两种。
第一种 通过
rush:xhtml;">
< select id = "sel" >
< option value = "1" >1 option >
< option value = "2" selected = "selected" >2 option >
< option value = "3" >3 option >
select >
第二种 为通过前端js来控制选中的项:
rush:xhtml;">
< script type = "text/javascript" >
function change(){
document.getElementById("sel")[2].selected=true;
}
script >
< select id = "sel" >
< option value = "1" >1 option >
< option value = "2" >2 option >
< option value = "3" >3 option >
select >
< input type = "button" value = "修改" onclick = "change()" />
rush:xhtml;">
var val = document.all.Item.options[document.all.Item.selectedindex].text
var i=document.getElementById( 'sel' ).options[document.getElementById( 'sel' ).selectedindex].value;
一些其它操作
1)动态创建select
rush:xhtml;">
function createSelect(){
var mySelect = document.createElement( "select" );
mySelect.id = "mySelect" ;
document.body.appendChild(mySelect);
}
2)添加选项option
rush:xhtml;">
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" ));
}
3)删除所有选项option
rush:xhtml;">
function removeAll(){
var obj=document.getElementById( 'mySelect' );
obj.options.length=0;
}
4)删除一个选项option
rush:xhtml;">
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);
}
5)获得选项option的值
rush:xhtml;">
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;
6)获得选项option的文本
rush:xhtml;">
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;
7)修改选项option
rush:xhtml;">
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" );
8)删除select
rush:xhtml;">
function removeSelect(){
var mySelect = document.getElementById( "mySelect" );
mySelect.parentNode.removeChild(mySelect);
}
以上这篇select标签设置默认选中的选项方法就是小编分享给大家的全部内容了,希望能给大家一个参考,也希望大家多多支持编程之家。