使用jQuery检查输入是否为空 [英] Check if inputs are empty using jQuery
问题描述
我有一个表格,希望填写所有字段.如果单击某个字段然后又不填写,则我要显示红色背景.
I have a form that I would like all fields to be filled in. If a field is clicked into and then not filled out, I would like to display a red background.
这是我的代码:
$('#apply-form input').blur(function () {
if ($('input:text').is(":empty")) {
$(this).parents('p').addClass('warning');
}
});
无论是否填写该字段,都将应用警告类.
It applies the warning class regardless of the field being filled in or not.
我在做什么错了?
推荐答案
$('#apply-form input').blur(function()
{
if( !$(this).val() ) {
$(this).parents('p').addClass('warning');
}
});
并且您不一定需要.length
或查看它是否为>0
,因为无论如何,空字符串的求值为假,但出于可读性考虑:
And you don't necessarily need .length
or see if it's >0
since an empty string evaluates to false anyway but if you'd like to for readability purposes:
$('#apply-form input').blur(function()
{
if( $(this).val().length === 0 ) {
$(this).parents('p').addClass('warning');
}
});
如果您确定它将始终对textfield元素进行操作,则可以使用this.value
.
If you're sure it will always operate on a textfield element then you can just use this.value
.
$('#apply-form input').blur(function()
{
if( !this.value ) {
$(this).parents('p').addClass('warning');
}
});
还应注意,如果只想引用一个单独的元素(假设上下文的后代/子对象中有一个文本字段),则$('input:text')
会捕获多个元素,指定上下文或使用this
关键字.
Also you should take note that $('input:text')
grabs multiple elements, specify a context or use the this
keyword if you just want a reference to a lone element (provided there's one textfield in the context's descendants/children).
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