[英]dissalow first option of drop down menu
How can I dissalow the first option of the following drop down menu (when "Go" is clicked, nothing should happen): 我该如何拒绝以下下拉菜单的第一个选项(单击“执行”时,什么也不会发生):
HTML : HTML:
<form name="form_name">
<select name="ddmenu_name">
<option>1st option (should do nothing)</option>
<option value="link 1">link 1 name</option>
<option value="link 2">link 2 name</option>
<option value="link 3">link 3 name</option>
<option value="link 4">link 4 name</option>
<input type="button" name="Submit" value="Go" onClick="window.open(ddmenu_name.value,'newtab')">
</select>
</form>
Thank you! 谢谢!
If the purpose of the first option is to provide a header, use an optgroup
: 如果第一个选项的目的是提供标题,请使用
optgroup
:
<select name="ddmenu_name">
<optgroup label="1st option (should do nothing)">
<option value="link 1">link 1 name</option>
<option value="link 2">link 2 name</option>
<option value="link 3">link 3 name</option>
<option value="link 4">link 4 name</option>
</optgroup>
</select>
Works in all major (old and new) browsers. 适用于所有主要(新旧)浏览器。 Doesn't require JavaScript.
不需要JavaScript。
If that wasn't the intention you could do something like this: 如果这不是您的意图,则可以执行以下操作:
var previous;
$('#ddmenu_id').on('change', function() {
if ($(this).val() === 'noselect') {
$(this).val(previous);
}
else {
previous = $(this).val();
}
});
With HTML: 使用HTML:
<select name="ddmenu_name" id="ddmenu_id">
<option value="noselect">1st option (should do nothing)</option>
<option value="link 1">link 1 name</option>
<option value="link 2">link 2 name</option>
<option value="link 3">link 3 name</option>
<option value="link 4">link 4 name</option>
</select>
<input type="button" name="Submit" value="Go" onClick="window.open(ddmenu_name.value,'newtab')">
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