JSFiddle - React, Tailwind, and code Playground

HTML

<a href="/Main/Index" onclick="return OnIndexCall(this)">Home</a>

JavaScript

function OnIndexCall(elem){
    var a=10;
    var b=a+20;
    $(elem).attr('href', $(elem).attr('href') + '?a=' + a + '&b=' + b);
    var a1 = $(elem).attr('href')
    alert(a1)
    return false;
}