jsplect初始化赋值_⽤JS怎么给lect标签设置动态的默认
值？
第⼀种通过的属性来设置选中项，此⽅法可以在动态语⾔如php在后台根据需要控制输出结果。
< lect id = "l" >
< option value = "1" >1 option >
< option value = "2" lected = "lected" >2 option >
< option value = "3" >3 option >
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lect >
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第⼆种为通过前端js来控制选中的项:
< script type = "text/javascript" >
function change(){
}
script >
留学法国< lect id = "l" >
< option value = "1" >1 option >
< option value = "2" >2 option >
< option value = "3" >3 option >
描写大象的句子lect >
< input type = "button" value = "修改" onclick = "change()" />
获取标签选中项⽂本的js代码为:
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var val = document.all.Item.options[document.all.Item.lectedIndex].text
var ElementById( ‘l‘ ).ElementById( ‘l‘ ).lectedIndex].value;
⼀些其它操作标签的技巧如下：
1)动态创建lect
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function createSelect(){
var mySelect = ateElement( "lect" );
mySelect.id = "mySelect" ;
藏装document.body.appendChild(mySelect);
}胃溃疡饮食
2)添加选项option
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function addOption(){
//根据id查找对象，
var ElementById( ‘mySelect‘ );
//添加⼀个选项
obj.add( new Option( "⽂本" , "值" ));
}
3)删除所有选项option墨子怒耕柱子
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function removeAll(){
var ElementById( ‘mySelect‘ );
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obj.options.length=0;
}
4)删除⼀个选项option
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function removeOne(){
var ElementById( ‘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.lectedIndex;
ve(index);
}
5)获得选项option的值
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var ElementById( ‘mySelect‘ );
var index=obj.lectedIndex; //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
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var ElementById( ‘mySelect‘ );
var index=obj.lectedIndex; //序号，取当前选中选项的序号var val = obj.options[index].text;
7)修改选项option
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var ElementById( ‘mySelect‘ );
var index=obj.lectedIndex; //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lect
脚部按摩器
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function removeSelect(){
var mySelect = ElementById( "mySelect" ); veChild(mySelect);
}
