form-window.html

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

<head>
    <title>Add Customer</title>
</head>

<body>
    <form>
        <div>
            <label>Name</label>
            <input type="text" id="name" autofocus>
        </div>
        <button type="submit">Submit</button>
    </form>

    <script>
        const electron = require('electron');
        const { ipcRenderer } = electron;

        const form = document.querySelector('form');
        form.addEventListener('submit', submitForm);

        function submitForm(e) {
            e.preventDefault();
            const name = document.querySelector('#name');
            ipcRenderer.send('customer:add', name.value);
        }
    </script>
</body>

</html>