Let's look at some ways you can get the first element by class name using JavaScript.
Here is the example html:
HTML
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>wecode101 Get first element using class name</title>
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC" crossorigin="anonymous">
</head>
<body>
<main>
<!--Main layout-->
<div class="container">
<div class="col-9 pt-5 mx-auto">
<div class="txt">Lemon</div>
<div class="txt">Orange</div>
<div class="txt">Lime</div>
<div class="txt">Grape</div>
</div>
</div>
</main>
</body>
</html>
JS
Option 1. Use querySelectorAll() and class selector with pseudo-class
let frt = document.querySelectorAll(".txt:first-child");
console.log(frt[0].innerText);//Lemon
Option 2. Use querySelectorAll() method
let frt = document.querySelectorAll(".txt");
console.log(frt[0].innerText);//Lemon
Option 3. Use getElementsByClassName() to create object, then convert NodeList object to array using Array.from() method to get first position using the index.
let frt = document.getElementsByClassName("txt");
console.log(Array.from(frt)[0].innerText);