是否可以使用JavaScript打开HTML选项以显示其选项列表？
答案 0 :(得分：79)
不幸的是，对这个问题有一个简单的答案，而且它是“不”
答案 1 :(得分：27)
适用于Google Chrome
dropDown = function (elementId) {
var dropdown = document.getElementById(elementId);
try {
showDropdown(dropdown);
} catch(e) {
}
return false;
};
showDropdown = function (element) {
var event;
event = document.createEvent('MouseEvents');
event.initMouseEvent('mousedown', true, true, window);
element.dispatchEvent(event);
};
答案 2 :(得分：24)
我使用此...但它需要用户点击选择框...
以下是2个javascript函数
function expand(obj)
{
obj.size = 5;
}
function unexpand(obj)
{
obj.size = 1;
}
然后我创建了选择框
<select id="test" multiple="multiple" name="foo" onFocus="expand(this)" onBlur="unexpand(this)">
<option >option1</option>
<option >option2</option>
<option >option3</option>
<option >option4</option>
<option >option5</option>
</select>
我知道这段代码有点晚了，但我希望它可以帮助那些和我有同样问题的人。
PS / FYI 我没有测试上面的代码（我动态创建我的选择框），我写的代码只在FireFox中测试过。
答案 3 :(得分：23)
我遇到了这个问题......并找到了一个可行的解决方案。
在用户点击一些纯HTML之前，我不希望显示选择框。所以我用opacity=.01覆盖了select元素。点击后，我将其更改回opacity=100。这允许我隐藏选择，当用户点击文本时，选择出现时显示选项。
答案 4 :(得分：3)
我很确定答案是：不。你可以用JavaScript选择但不能打开选择。您必须使用自定义解决方案。
答案 5 :(得分：3)
现在已经很晚了，但我认为如果他们引用这个问题对某人有用。我相信下面的JS会做什么问题。
<script>
$(document).ready(function()
{
document.getElementById('select').size=3;
});
</script>
答案 6 :(得分：3)
我提供的解决方案安全，简单并且与Internet Explorer，FireFox和Chrome兼容。
这种方法是新的和完整的。我没有发现任何与互联网上的解决方案相同的东西。简单，跨浏览器（Internet Explorer，Chrome和Firefox），保留布局，使用选择本身，易于使用。
注意：JQuery是必需的。
HTML CODE
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>CustonSelect</title>
<script type="text/javascript" src="./jquery-1.3.2.js"></script>
<script type="text/javascript" src="./CustomSelect.js"></script>
</head>
<div id="testDiv"></div>
<body>
<table>
<tr>
<td>
<select id="Select0" >
<option value="0000">0000</option>
<option value="0001">0001</option>
<option value="0002">0002</option>
<option value="0003">0003</option>
<option value="0004">0004</option>
<option value="0005">0005</option>
<option value="0006">0006</option>
<option value="0007">0007</option>
<option value="0008">0008</option>
<option value="0009">0009</option>
<option value="0010">0010</option>
<option value="0011">0011</option>
<option value="0012">0012</option>
<option value="0013">0013</option>
<option value="0014">0014</option>
<option value="0015">0015</option>
<option value="0016">0016</option>
<option value="0017">0017</option>
<option value="0018">0018</option>
<option value="0019">0019</option>
<option value="0020">0020</option>
<option value="0021">0021</option>
<option value="0022">0022</option>
<option value="0023">0023</option>
<option value="0024">0024</option>
<option value="0025">0025</option>
<option value="0026">0026</option>
<option value="0027">0027</option>
<option value="0028">0028</option>
<option value="0029">0029</option>
<option value="0030">0030</option>
<option value="0031">0031</option>
<option value="0032">0032</option>
<option value="0033">0033</option>
<option value="0034">0034</option>
<option value="0035">0035</option>
<option value="0036">0036</option>
<option value="0037">0037</option>
<option value="0038">0038</option>
<option value="0039">0039</option>
<option value="0040">0040</option>
</select>
</td>
</tr>
<tr>
<td>
<select id="Select1" >
<option value="0000">0000</option>
<option value="0001">0001</option>
<option value="0002">0002</option>
<option value="0003">0003</option>
<option value="0004">0004</option>
<option value="0005">0005</option>
<option value="0006">0006</option>
<option value="0007">0007</option>
<option value="0008">0008</option>
<option value="0009">0009</option>
<option value="0010">0010</option>
<option value="0011">0011</option>
<option value="0012">0012</option>
<option value="0013">0013</option>
<option value="0014">0014</option>
<option value="0015">0015</option>
<option value="0016">0016</option>
<option value="0017">0017</option>
<option value="0018">0018</option>
<option value="0019">0019</option>
<option value="0020">0020</option>
<option value="0021">0021</option>
<option value="0022">0022</option>
<option value="0023">0023</option>
<option value="0024">0024</option>
<option value="0025">0025</option>
<option value="0026">0026</option>
<option value="0027">0027</option>
<option value="0028">0028</option>
<option value="0029">0029</option>
<option value="0030">0030</option>
<option value="0031">0031</option>
<option value="0032">0032</option>
<option value="0033">0033</option>
<option value="0034">0034</option>
<option value="0035">0035</option>
<option value="0036">0036</option>
<option value="0037">0037</option>
<option value="0038">0038</option>
<option value="0039">0039</option>
<option value="0040">0040</option>
</select>
</td>
</tr>
<tr>
<td>
<select id="Select2" >
<option value="0000">0000</option>
<option value="0001">0001</option>
<option value="0002">0002</option>
<option value="0003">0003</option>
<option value="0004">0004</option>
<option value="0005">0005</option>
<option value="0006">0006</option>
<option value="0007">0007</option>
<option value="0008">0008</option>
<option value="0009">0009</option>
<option value="0010">0010</option>
<option value="0011">0011</option>
<option value="0012">0012</option>
<option value="0013">0013</option>
<option value="0014">0014</option>
<option value="0015">0015</option>
<option value="0016">0016</option>
<option value="0017">0017</option>
<option value="0018">0018</option>
<option value="0019">0019</option>
<option value="0020">0020</option>
<option value="0021">0021</option>
<option value="0022">0022</option>
<option value="0023">0023</option>
<option value="0024">0024</option>
<option value="0025">0025</option>
<option value="0026">0026</option>
<option value="0027">0027</option>
<option value="0028">0028</option>
<option value="0029">0029</option>
<option value="0030">0030</option>
<option value="0031">0031</option>
<option value="0032">0032</option>
<option value="0033">0033</option>
<option value="0034">0034</option>
<option value="0035">0035</option>
<option value="0036">0036</option>
<option value="0037">0037</option>
<option value="0038">0038</option>
<option value="0039">0039</option>
<option value="0040">0040</option>
</select>
</td>
</tr>
<tr>
<td>
<select id="Select3" >
<option value="0000">0000</option>
<option value="0001">0001</option>
<option value="0002">0002</option>
<option value="0003">0003</option>
<option value="0004">0004</option>
<option value="0005">0005</option>
<option value="0006">0006</option>
<option value="0007">0007</option>
<option value="0008">0008</option>
<option value="0009">0009</option>
<option value="0010">0010</option>
<option value="0011">0011</option>
<option value="0012">0012</option>
<option value="0013">0013</option>
<option value="0014">0014</option>
<option value="0015">0015</option>
<option value="0016">0016</option>
<option value="0017">0017</option>
<option value="0018">0018</option>
<option value="0019">0019</option>
<option value="0020">0020</option>
<option value="0021">0021</option>
<option value="0022">0022</option>
<option value="0023">0023</option>
<option value="0024">0024</option>
<option value="0025">0025</option>
<option value="0026">0026</option>
<option value="0027">0027</option>
<option value="0028">0028</option>
<option value="0029">0029</option>
<option value="0030">0030</option>
<option value="0031">0031</option>
<option value="0032">0032</option>
<option value="0033">0033</option>
<option value="0034">0034</option>
<option value="0035">0035</option>
<option value="0036">0036</option>
<option value="0037">0037</option>
<option value="0038">0038</option>
<option value="0039">0039</option>
<option value="0040">0040</option>
</select>
</td>
</tr>
<tr>
<td>
<select id="Select4" >
<option value="0000">0000</option>
<option value="0001">0001</option>
<option value="0002">0002</option>
<option value="0003">0003</option>
<option value="0004">0004</option>
<option value="0005">0005</option>
<option value="0006">0006</option>
<option value="0007">0007</option>
<option value="0008">0008</option>
<option value="0009">0009</option>
<option value="0010">0010</option>
<option value="0011">0011</option>
<option value="0012">0012</option>
<option value="0013">0013</option>
<option value="0014">0014</option>
<option value="0015">0015</option>
<option value="0016">0016</option>
<option value="0017">0017</option>
<option value="0018">0018</option>
<option value="0019">0019</option>
<option value="0020">0020</option>
<option value="0021">0021</option>
<option value="0022">0022</option>
<option value="0023">0023</option>
<option value="0024">0024</option>
<option value="0025">0025</option>
<option value="0026">0026</option>
<option value="0027">0027</option>
<option value="0028">0028</option>
<option value="0029">0029</option>
<option value="0030">0030</option>
<option value="0031">0031</option>
<option value="0032">0032</option>
<option value="0033">0033</option>
<option value="0034">0034</option>
<option value="0035">0035</option>
<option value="0036">0036</option>
<option value="0037">0037</option>
<option value="0038">0038</option>
<option value="0039">0039</option>
<option value="0040">0040</option>
</select>
</td>
</tr>
</table>
<input type="button" id="Button0" value="MoveLayout!"/>
</body>
</html>
JAVASCRIPT CODE
var customSelectFields = new Array();
// Note: The list of selects to be modified! By Questor
customSelectFields[0] = "Select0";
customSelectFields[1] = "Select1";
customSelectFields[2] = "Select2";
customSelectFields[3] = "Select3";
customSelectFields[4] = "Select4";
$(document).ready(function()
{
//Note: To debug! By Questor
$("#Button0").click(function(event){ AddTestDiv(); });
StartUpCustomSelect(null);
});
//Note: To test! By Questor
function AddTestDiv()
{
$("#testDiv").append("<div style=\"width:100px;height:100px;\"></div>");
}
//Note: Startup selects customization scheme! By Questor
function StartUpCustomSelect(what)
{
for (i = 0; i < customSelectFields.length; i++)
{
$("#" + customSelectFields[i] + "").click(function(event){ UpCustomSelect(this); });
$("#" + customSelectFields[i] + "").wrap("<div id=\"selectDiv_" + customSelectFields[i] + "\" onmouseover=\"BlockCustomSelectAgain();\" status=\"CLOSED\"></div>").parent().after("<div id=\"coverSelectDiv_" + customSelectFields[i] + "\" onclick=\"UpOrDownCustomSelect(this);\" onmouseover=\"BlockCustomSelectAgain();\"></div>");
//Note: Avoid breaking the layout when the CSS is modified from "position" to "absolute" on the select! By Questor
$("#" + customSelectFields[i] + "").parent().css({'width': $("#" + customSelectFields[i] + "")[0].offsetWidth + 'px', 'height': $("#" + customSelectFields[i] + "")[0].offsetHeight + 'px'});
BlockCustomSelect($("#" + customSelectFields[i] + ""));
}
}
//Note: Repositions the div that covers the select using the "onmouseover" event so
//Note: if element on the screen move the div always stand over it (recalculate! By Questor
function BlockCustomSelectAgain(what)
{
for (i = 0; i < customSelectFields.length; i++)
{
if($("#" + customSelectFields[i] + "").parent().attr("status") == "CLOSED")
{
BlockCustomSelect($("#" + customSelectFields[i] + ""));
}
}
}
//Note: Does not allow the select to be clicked or clickable! By Questor
function BlockCustomSelect(what)
{
var coverSelectDiv = $(what).parent().next();
//Note: Ensures the integrity of the div style! By Questor
$(coverSelectDiv).removeAttr('style');
//Note: To resolve compatibility issues! By Questor
var backgroundValue = "";
var filerValue = "";
if(navigator.appName == "Microsoft Internet Explorer")
{
backgroundValue = 'url(fakeimage)';
filerValue = 'progid:DXImageTransform.Microsoft.AlphaImageLoader(enabled=true, sizingMethod=\'scale\', src=\'fakeimage\' )';
}
//Note: To debug! By Questor
//'border': '5px #000 solid',
$(coverSelectDiv).css({
'position': 'absolute',
'top': $(what).offset().top + 'px',
'left': $(what).offset().left + 'px',
'width': $(what)[0].offsetWidth + 'px',
'height': $(what)[0].offsetHeight + 'px',
'background': backgroundValue,
'-moz-background-size':'cover',
'-webkit-background-size':'cover',
'background-size':'cover',
'filer': filerValue
});
}
//Note: Allow the select to be clicked or clickable! By Questor
function ReleaseCustomSelect(what)
{
var coverSelectDiv = $(what).parent().next();
$(coverSelectDiv).removeAttr('style');
$(coverSelectDiv).css({'display': 'none'});
}
//Note: Open the select! By Questor
function DownCustomSelect(what)
{
//Note: Avoid breaking the layout. Avoid that select events be overwritten by the others! By Questor
$(what).css({
'position': 'absolute',
'z-index': '100'
});
//Note: Open dropdown! By Questor
$(what).attr("size","10");
ReleaseCustomSelect(what);
//Note: Avoids the side-effect of the select loses focus.! By Questor
$(what).focus();
//Note: Allows you to select elements using the enter key when the select is on focus! By Questor
$(what).keyup(function(e){
if(e.keyCode == 13)
{
UpCustomSelect(what);
}
});
//Note: Closes the select when loses focus! By Questor
$(what).blur(function(e){
UpCustomSelect(what);
});
$(what).parent().attr("status", "OPENED");
}
//Note: Close the select! By Questor
function UpCustomSelect(what)
{
$(what).css("position","static");
//Note: Close dropdown! By Questor
$(what).attr("size","1");
BlockCustomSelect(what);
$(what).parent().attr("status", "CLOSED");
}
//Note: Closes or opens the select depending on the current status! By Questor
function UpOrDownCustomSelect(what)
{
var customizedSelect = $($(what).prev().children()[0]);
if($(what).prev().attr("status") == "CLOSED")
{
DownCustomSelect(customizedSelect);
}
else if($(what).prev().attr("status") == "OPENED")
{
UpCustomSelect(customizedSelect);
}
}
答案 7 :(得分：3)
在尝试解决这个问题一段时间后，我设法找到了一个有效的工作解决方案：
var event = new MouseEvent('mousedown');
element.dispatchEvent(event);
我也尝试在Jquery中实现此功能，使用trigger和mousedown或仅使用mousedown，但没有成功。
答案 8 :(得分：1)
至少在Geckos中，这可能是可能的。看这里：
编辑：我无法让它发挥作用;好像加雷斯是正确的......
答案 9 :(得分：-1)
<select id="myDropDown">
<option>html5</option>
<option>javascript</option>
<option>jquery</option>
<option>css</option>
<option>sencha</option>
</select>
通过jQuery：
var myDropDown=$("#myDropDown");
var length = $('#myDropDown> option').length;
//open dropdown
myDropDown.attr('size',length);
//close dropdown
myDropDown.attr('size',0);
通过javascript：
var myDropDown=document.getElementById("myDropDown");
var length = myDropDown.options.length;
//open dropdown
myDropDown.size = length;
//close dropdown
myDropDown.size = 0;
复制自： Open close select
答案 10 :(得分：-7)
//use jquery
$select.trigger('mousedown')