jQuery, using ! to say “not selected”

问题

Is it possible to do something like this to check if radio form is unchecked:

if !($(this).find("input:checked")) {}

what would be the correct syntax?

回答1:

Try this:

$(this).find("input:not(:checked)")

回答2:

Try this instead bc .find returns an array of DOM elements:

if ($(this).find("input:checked").length == 0) {}

回答3:

You can use .is for boolean test

if (!$(this).find('input').is(':checked')) { }

回答4:

First of all, you'll want that ! inside the conditional check:

if (!$(this).find("input:checked")) {}

Second of all, the .find method returns a jQuery object, so even if it found nothing, it will still be truthy.

What you'll probably want to check is the length of the jQuery object:

if (!$(this).find("input:checked").length) {}

If there are no elements, then etc etc etc

回答5:

I presume you're searching a parent element (e.g. a form) to see if you can find descendant checkboxes that are checked.

You want something like this:

if (!$(this).find('input:radio:checked').length) {

The condition passes if there are no descendant radio input elements that are checked.

来源：https://stackoverflow.com/questions/6048727/jquery-using-to-say-not-selected