JSFiddle - React, Tailwind, and code Playground

HTML

<input id="number" /><button id ="get-code" >Get Code</button>

<div id="country-code"></div>

JavaScript

document.getElementById("get-code").onclick = function() {
    
    cc = document.getElementById("number").value.split(document.getElementById("number").value.slice(-10))[0]
    document.getElementById("country-code").innerHTML = cc 
}