如何检查下拉菜单是否被禁用? [英] How to check if dropdown is disabled?

问题描述

使用jQuery，我如何简单地检查它是否为只读?

Using jquery how do i simply check if it is read only?

这就是我正在尝试的..

this is what i am trying..

$("#item").keydown(function (event) {
     //alert(event.keyCode);
     if (event.keyCode == 13) {
         $("#ok").click();               
         if ($('#dropLength').prop("disabled") == false) {
             $("#dropLength").focus();
             return;
         }
         if ($('#dropUnit').prop("disabled") == false) {
             $("#dropUnit").focus();
             return;
         }
         $("#qty").focus();                
         return ;
     }
 });

还使用jquery将下拉列表设置为只读:

The dropdowns are set to readonly using jquery also:

if ($('#dropLength').find('option').length <= 1) {
      $('#dropLength').attr("disabled", "disabled");
}
if ($('#dropUnit').find('option').length <= 1) {
      $('#dropUnit').attr("disabled", "disabled");
}   

推荐答案

1.6之前的旧解决方案是使用.attr并将返回的值作为bool处理.主要问题是返回的.attr类型已更改为string，因此与== true的比较中断了(请参见 http://jsfiddle.net/2vene/1/(并切换jquery版本).

The legacy solution, before 1.6, was to use .attr and handle the returned value as a bool. The main problem is that the returned type of .attr has changed to string, and therefore the comparison with == true is broken (see http://jsfiddle.net/2vene/1/ (and switch the jquery-version)).

1.6版引入了.prop，它返回了bool.

With 1.6 .prop was introduced, which returns a bool.

尽管如此，我建议使用 .is() ，因为返回的类型本质上是bool ，例如:

Nevertheless, I suggest to use .is(), as the returned type is intrinsically bool, like:

$('#dropUnit').is(':disabled');
$('#dropUnit').is(':enabled');

此外，.is()更自然(就自然语言"而言)，并且比简单的属性比较(例如:.is(':last')，.is(':visible')，...)添加了更多条件，请参阅关于选择器的文档).

Furthermore .is() is much more natural (in terms of "natural language") and adds more conditions than a simple attribute-comparison (eg: .is(':last'), .is(':visible'), ... please see documentation on selectors).

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