# JavaScript events

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This section shows you how to process events from a JavaScript context to:

-   Pass the current environment parameters to the web view.
-   Terminate the current session and process commands.
-   Handle messages that should be processed by the host app.

## Inject environment parameters into WebView

To pass the current environment parameters to the web view, you can simply load them as a JSON string.

```kotlin
// JSON data to be injected into the WebView as JavaScript
private const val JSON_DATA = """
    window.zoomCampaignSdkConfig = window.zoomCampaignSdkConfig || {
        language: 'user language',
        firstName: 'user first name',
        lastName: 'user last name',
        nickName: 'user nick name',
        address: 'user address',
        company: 'user company',
        email: 'user email',
        phoneNumber: 'user phone number'
    };
"""

// Inject JSON data as JavaScript into the WebView when the URL is loaded
private fun injectJsonDataFunction() {
    val js = "javascript: $JSON_DATA;"
    binding.webView.loadUrl(js)
}
```

> **Supported languages for language**
>
> `en-US`, `da-DK`, `de-DE`, `en-AU`, `en-GB`, `en-NZ`, `es-ES`, `es-MX`, `es-US`, `fr-CA`, `fr-FR`, `id-ID`, `it-IT`, `ja-JP`, `ko-KR`, `nl-NL`, `pl-PL`, `pt-BR`, `pt-PT`, `ro-RO`, `ru-RU`, `sv-SE`, `tr-TR`, `vi-VN`, `zh-CN`, `zh-TW`

## Handle exit callback functions

To handle the termination of the current session and process commands from the JavaScript context, create a `JavascriptInterface` function.

Here is an example.

```kotlin
// Inject JavaScript handler functions into the WebView when the URL is loaded
private fun injectJavaScriptFunction() {
    val js = """
        javascript: window.addEventListener('zoomCampaignSdk:ready', () => {
            if (window.zoomCampaignSdk) {
                window.zoomCampaignSdk.native = {
                    exitHandler: {
                        handle: function() {
                            $EXIT_HANDLER_NAME.handleExit();
                        }
                    },
                    commonHandler: {
                        handle: function(e) {
                            $COMMON_HANDLER_NAME.handleCommon(JSON.stringify(e));
                        }
                    }
                };
            }
        });
    """.trimIndent()

    binding.webView.loadUrl(js)
}

// JavaScript interface method to handle exit commands
@JavascriptInterface
fun handleExit() {
    //Your code
}
```

## Handle handoff events

Create a `JavascriptInterface` to handle messages from the JavaScript context that the host app should process.

```kotlin
// Inject handleHandoff function into the WebView when the URL is loaded
private fun injectHandoffFunction() {
    val js = """
        javascript: window.addEventListener('support_handoff', (e) => {
            $SUPPORT_HANDOFF_HANDLER_NAME.handleHandoff(JSON.stringify(e.detail));
        });
    """.trimIndent()

    binding.webView.loadUrl(js)
}

// JavaScript interface method to handle handoff commands
@JavascriptInterface
fun handleHandoff(e: String?) {
    //Your code
}
```