JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/dot-luv/jquery-ui.css">
<div id="myDiv">
    <input type="checkbox" />
    <input type="checkbox" />
    <input type="checkbox" />
</div>

JavaScript

$('#myDiv :checkbox').attr('checked', 'checked');
alert($('#myDiv :checkbox').attr('checked'));