jquery 如果文本输入不*不*等于空白
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jquery if text input does *not* equal blank
提问by Adi
I am trying to work out how to do something if a certain text box is notempty (i.e. contain something, could be anything)
如果某个文本框不为空（即包含某些内容，可以是任何内容），我正在尝试弄清楚如何做某事
This is my code (that doesnt seem to work)
这是我的代码（似乎不起作用）
if ( !($('#edit-sPostalCode').attr('val','')) ) {
stuff here
}
What have I missed?
我错过了什么？
回答by El Ronnoco
if ( $('#edit-sPostalCode').val() != '' ) {
stuff here
}
$('#edit-sPostalCode').attr('val','')will actually create an attribute of the input box with a value of ''and will then return a jQuery object.
$('#edit-sPostalCode').attr('val','')实际上将创建一个值为 的输入框的属性，''然后将返回一个 jQuery 对象。
Saying !($('#edit-sPostalCode').attr('val',''))will then negate that jQuery object. As an instance of an object is truthyin JS the result of this expression will always be false.
Saying!($('#edit-sPostalCode').attr('val',''))然后将否定该 jQuery 对象。由于对象的实例在 JS 中是真实的，因此该表达式的结果将始终为false.
回答by Blazemonger
Are you aware of the .valmethod?
你知道.val方法吗？
if ( $('#edit-sPostalCode').val() !== '' ) {
Although you ought to $.trimthe value if you consider whitespace as being equivalent to nothing at all:
尽管$.trim如果您认为空格等于什么都没有，则应该考虑该值：
if ( $.trim( $('#edit-sPostalCode').val() ) !== '' ) {
回答by Nicholas Murray
if ( !($('#edit-sPostalCode').val() === '') ) {
stuff here
}
