How to show the keyboard when an input field is clicked?

If you want to show the native Android or iOS keyboard, please enable WebViewPrefab.NativeOnScreenKeyboardEnabled. If you instead want to show 3D WebView's Keyboard prefab or a custom keyboard when an input field in the webview is clicked, you can use the IWebView.FocusedInputFieldChanged event to detect when a text input is focused and then hide or show the keyboard in response to that. Here's an example:

using UnityEngine;
using Vuplex.WebView;

class Example : MonoBehaviour {

    // Set these fields via the Editor.
    // https://support.vuplex.com/articles/how-to-reference-a-webview
    public WebViewPrefab webViewPrefab;
    public Keyboard keyboard;

    async void Start() {

        // Hide the keyboard after it initializes so that it's initially hidden.
        await keyboard.WaitUntilInitialized();
        keyboard.gameObject.SetActive(false);

        // Use the FocusedInputFieldChanged event to hide or show the Keyboard based on whether an input field is focused.
        await webViewPrefab.WaitUntilInitialized();
        webViewPrefab.WebView.FocusedInputFieldChanged += (sender, eventArgs) => {
            var shouldShowKeyboard = eventArgs.Type != FocusedInputFieldType.None;
            keyboard.gameObject.SetActive(shouldShowKeyboard);
        };
    }
}