JSFiddle - React, Tailwind, and code Playground

HTML

<p>The below box is checked, but marked indeterminate. If it were part of a form, it would be submitted normally (indeterminate value has no effect on form submission). However, it isn't properly matched with the <strong>:checked</strong> selector by jQuery in WebKit browsers.</p>

<input type='checkbox' checked />

CSS

p span { color: green }

JavaScript

// make the input box indeterminate (but still checked!)
var $input = $('input');
$input.get(0).indeterminate=true;

// display if the item matches the test
log( ".is(':checked')", $input.is(':checked') );

if( document.body.webkitMatchesSelector )
{
    log( ".webkitMatchesSelector(':checked')", 
         $input.get(0).webkitMatchesSelector(':checked'));
}

// some
if( $input.prop )
    log( ".prop('checked')", $input.prop('checked') );

// little function for logging
function log(label, result)
{
    $('<p>'+label+': <span>'+result+'</span></p>')
    .appendTo('body');
}