JavaScript Document getElementById() Method

// HTML: <p id="para">Hello DOM</p>
const elem = document.getElementById("para");
console.log(elem !== null);      // true
console.log(elem.textContent);   // "Hello DOM"
console.log(elem.id);            // "para"

const missing = document.getElementById("no-such-id");
console.log(missing); // null

if (missing) {
  console.log(missing.textContent);
} else {
  console.log("not found");
}

// HTML: <div id="Main">Box</div>
const ok = document.getElementById("Main");
const bad = document.getElementById("main");

console.log(ok !== null);  // true
console.log(bad);          // null

// Flexible alternative when you need a selector:
const viaQs = document.querySelector("#Main");
console.log(viaQs === ok); // true