JSFiddle - React, Tailwind, and code Playground
HTML
<input type="text" id="from" />
<input type="text" id="to" />
<input type="button" id="switch_cities" value="Switch" />
JavaScript
$(document).off("click", "#switch_cities").on("click", "#switch_cities", function(e) {
alert('uuuu');
e.preventDefault();
var r = $("#from").val(),
t = $("#to").val();
("" != r || "" != t) && ($("#from").val(t), $("#to").val(r))
})