隐藏/显示辅助选择中的所选选项 [英] Hide/show the selected option on a secondary select
问题描述
我有两个具有不同ID的<select>
元素.
I have two <select>
elements with different IDs.
当用户从第一个选择框中选择一个值时,我希望第二个选择框仅显示连接的值.
When the user selects a value from the first select box, I want the second select box to only display connected values.
我的代码:
<select id="ExtraField_1" name="ExtraField_1">
<option value="1">test1</option>
<option value="2">test2</option>
<option value="3">test3</option>
<option value="4">test4</option>
<option value="5">test5</option>
<option value="6">test6</option>
<option value="7">test7</option>
<option value="8">test8</option>
<option value="9">test9</option>
<option value="10">test10</option>
<option value="11">test11</option>
<option value="12">test12</option>
</select>
<select id="ExtraField_2" name="ExtraField_2">
<option value="1">test1</option>
<option value="2">test2</option>
<option value="3">test3</option>
<option value="4">test4</option>
<option value="5">test5</option>
<option value="6">test6</option>
<option value="7">test7</option>
<option value="8">test8</option>
<option value="9">test9</option>
<option value="10">test10</option>
<option value="11">test11</option>
<option value="12">test12</option>
<option value="13">test13</option>
<option value="14">test14</option>
<option value="15">test15</option>
<option value="16">test16</option>
<option value="17">test17</option>
<option value="18">test18</option>
<option value="19">test19</option>
<option value="20">test20</option>
</select>
因此,当用户从第一个选择框中选择"test1"时,他在第二个选择框中将仅看到"test2","test3"和"test4";从第一个开始的"test2"将在第二个框中显示"test6","test7"和"test8".
So when user selects "test1" from first select boxm he will see only "test2", "test3" and "test4" on the second select box; "test2" from first will show "test6", "test7" and "test8" in the second box.
如何使用JavaScript解决此问题?
How can I use JavaScript to resolve this problem?
推荐答案
如果可以使用jQuery,则始终可以清除并将选项附加到第二个选择项上.
If you can use jQuery then you can always just clear and append the options to the second select.
$('#ExtraField_1').change(function(){
$('#ExtraField_2').find('option').remove()
if($(this).val() == '1'){
$('#ExtraField_2').append($("<option </option>").attr('value','2').text('test2'));
$('#ExtraField_2').append($("<option></option>").attr('value','3').text('test3'));
$('#ExtraField_2').append($("<option></option>").attr('value','4').text('test4'));
}
if($(this).val() == '2'){
$('#ExtraField_2').append($("<option></option>").attr('value','5').text('test5'));
$('#ExtraField_2').append($("<option></option>").attr('value','6').text('test6'));
$('#ExtraField_2').append($("<option></option>").attr('value','7').text('test7'));
}
});
仅使用javascript有点复杂,但是我仍然会采用相同的方法.
using only javascript is a bit more complicated but I would still take the same approach.
function createOption(otext,oValue){
var newOption = document.createElement('option');
newOption.text = otext;
newOption.value = oValue;
return newOption;
}
function clearSelect(theSelect){
for(var i = 0;i <= theSelect.options.length+1;i++)
{
theSelect.remove();
}
}
function onSelect(theSelect){
var nextSelect = document.getElementById('ExtraField_2');
clearSelect(nextSelect);
var selected = theSelect.options[theSelect.selectedIndex];
if(selected.value == 1){
nextSelect.add(createOption('test2','2'));
nextSelect.add(createOption('test3','3'));
nextSelect.add(createOption('test4','4'));
}
if(selected.value == 2){
nextSelect.add(createOption('test5','5'));
nextSelect.add(createOption('test6','6'));
nextSelect.add(createOption('test7','7'));
}
}
使用html:
<select id="ExtraField_1" name="ExtraField_1" onchange="javascript: onSelect(this);" >
<option value="0">Select a test..</option>
<option value="1">test1</option>
<option value="2">test2</option>
<option value="3">test3</option>
<option value="4">test4</option>
<option value="5">test5</option>
<option value="6">test6</option>
<option value="7">test7</option>
<option value="8">test8</option>
<option value="9">test9</option>
<option value="10">test10</option>
<option value="11">test11</option>
<option value="12">test12</option>
</select>
<select id="ExtraField_2" name="ExtraField_2">
<option value="0">Select from the left</option>
</select>
如您所见,
仍然可以实现您的期望,但是您没有隐藏任何选项.
as you can see it still does what you expect but you are not hiding options.
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