js/FileReader_API.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>File Reader API Demo</title>
    <style>
        .wrapper {
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
        }

        input {
            border: 1px solid lightgray;
            padding: .5rem;
            border-radius: 4px;
        }

        .avatar-container img {
            width: 150px;
            height: 150px;
            border-radius: 50%;
        }
    </style>
</head>

<body>
    <div class="wrapper">
        <div class="avatar-container">
            <img src="https://via.placeholder.com/150" alt="avatar-image">
        </div>
        <input type="file" name="avatar" id="avatar">
    </div>
    <script>
        const avatar = document.getElementById('avatar');

        avatar.addEventListener('change', (event) => {
            const reader = new FileReader();
            reader.readAsDataURL(event.target.files[0]);
            reader.onload = () => {
                const img = document.querySelector('.avatar-container img');
                img.src = reader.result;
            };
        });
    </script>
</body>

</html>