JSFiddle - React, Tailwind, and code Playground
by bgmort
HTML
<input type="radio" name="rd" value="yes" /> Yes <br/>
<input type="radio" name="rd" value="no" /> No <br/>
<input type="checkbox" name="cb" value="yea" /> Yea <br/>
<input type="checkbox" name="cb" value="nay" /> Nay <br/>
JavaScript
$(':radio').first().prop('checked', true);
$(':checkbox').first().prop('checked', true);
var testcases = [
//failures
$('input[type="radio"][checked]'),
$('input[type="checkbox"][checked]'),
$('input[name="rd"][checked]'),
$('input[name="cb"][checked]'),
$('input[name][type][checked]'),
//working selectors
$('input[type="radio"]').filter('[checked]'),
$('input[type="radio"]').filter(':checked'),
$('input[type="radio"]:checked'),
$(':radio').filter('[checked]'),
$(':radio').filter(':checked'),
$(':radio:checked'),
$(':radio[checked]'),
$('input[type="checkbox"]').filter('[checked]'),
$('input[type="checkbox"]').filter(':checked'),
$('input[type="checkbox"]:checked'),
$(':checkbox').filter('[checked]'),
$(':checkbox').filter(':checked'),
$(':checkbox:checked'),
$(':checkbox[checked]'),
$('input[name="rd"]').filter('[checked]'),
$('input[name="cb"]').filter('[checked]'),
$('input[name][type]'),
];
var fails = [];
$.each(testcases, function(i, el){
if (!el.length)
fails.push(i+1);
});
if(fails.length)
alert('The following tests failed: ' + fails.join(', '));