index.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>tool_country-phone-code-gen Output</title>
</head>
<body>
    <select id="aus-country">
        <option value="">Select Country</option>
    </select>
    <script>
        //Get the Data
        fetch('./out/list.json')
        .then(function(response) {
            return response.json();
        })
        //Create the Select Dropdown
        .then(function(result){
            const sel = document.querySelector('#aus-country');
            let op;
            for(var k in result){
                op = document.createElement('option');
                op.value = `+${result[k]}`;
                op.text=k;
                sel.appendChild(op);
            }
        });
    </script>
</body>
</html>