JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="q" />
<input type="button" value="search!" onclick="gsearch();" />

JavaScript

function gsearch() {
    var q=document.getElementById('q').value;
    q+=' site:example.com';
    window.open('http://www.google.com/search?q='+encodeURIComponent(q));
    
}