JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" name="boxone" value=""><br>
<input type="text" name="boxtwo" value=""><br>
<input type="button" value="Submit" onclick="swap();" />

JavaScript

function swap(){
var a = document.getElementsByName('boxone')[0];
var b = document.getElementsByName("boxtwo")[0];
[a.value, b.value]=[b.value, a.value];
   // alert (a.value);
/*var i=a.value;
a.value=b.value;
b.value=i;
*/
}