JSFiddle - React, Tailwind, and code Playground
HTML
<input type="text" id="address1" value="" />
<input type="checkbox" id="copyAddress" />
<input type="text" id="address2" value="" />
JavaScript
$('#copyAddress').click(function () {
if ($(this).prop('checked')) {
$('#address2').val($('#address1').val());
} else {
$('#address2').val('');
}
});