> For the complete documentation index, see [llms.txt](https://firstoken.gitbook.io/api-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://firstoken.gitbook.io/api-docs/guides/implementing-captures-sdk-js/functions.md).

# Functions

### `FTCaptures.init(...)`

This function initializes the configuration for a specific route in a given environment. Here is an explanation of how the function works:

The function takes three parameters: 

1. `routeID` (the ID of the route)
2. `environment` (the environment in which the route is being initialized)
3. `callback` (a function to be executed after the initialization is complete)
4. `tags` (an array of  tags to identify the permanent token). *Optional*\
   *(Only is utilized when the inbound route has been set up with a permanent token)*.
5. `jwtToken` (a JWT token) - Optional\
   *Note: Only applicable in version 2.3*

<pre><code><strong>const FT = window.FTCaptures.init("&#x3C;ROUTE_ID>", "production", function (state) { }, tags, jwtToken);
</strong></code></pre>

### `FTCaptures.on(...)`

This function provides a convenient way to register multiple event handlers for different events and allows for easy execution of the registered callbacks when the corresponding events occur.

You can use the `on` function to subscribe to the following events:&#x20;

{% tabs %}
{% tab title="For Validation Failed" %}

* cardHolderValidationFailed
* cardNumberValidationFailed
* cardExpirationDateValidationFailed
* cardSecurityCodeValidationFailed
* expirationYearValidationFailed
* expirationMonthValidationFailed
* textValidationFailed
* AmountValidationFailed
* selectValidationFailed
* radioValidationFailed
  {% endtab %}

{% tab title="For Validation Success" %}

* cardHolderValidationSuccess
* cardNumberValidationSuccess
* cardExpirationDateValidationSuccess
* cardSecurityCodeValidationSuccess
* expirationYearValidationSuccess
* expirationMonthValidationSuccess
* textValidationSuccess
* AmountValidationSuccess
* selectValidationSuccess
* radioValidationSuccess
  {% endtab %}
  {% endtabs %}

Here's an example of how you can subscribe to an event:

```
FTCaptures.on("cardNumberValidationFailed", function (event) {
    //Do something with the event
    
});
```

### `FT.field(...)`

Field function creates a field within a specified container using an `<iframe>`. Here is an explanation of how the function works:

1. The function takes two parameters:&#x20;
   * `selector` (the id selector for the container element)&#x20;
   * `options` (an object containing configuration options for the field).
2. It checks if the `routeID` property is set. If not, it throws an error indicating that the SDK must be initialized before creating fields.

### `FTCaptures.tokenize(...)`

Tokenize function prepares the fields within a specified route for tokenization. Here is an explanation of how the function works:

1. The function takes one parameter: `routeID` (the ID of the route).
2. It sets the `routeID` property of the current object (`this`) to the provided `routeID`.
3. The function returns a new Promise that takes two parameters: `resolve` and `reject`. These parameters are used to handle the asynchronous result of the tokenization process.

### `FTCaptures.validate(...)`

The `validate` function performs field validation for a specified route. Here is an explanation of how the function works:

1. The function takes one parameter: `routeID` (the ID of the route).
2. The function returns a new Promise that takes two parameters: `resolve` and `reject`. These parameters are used to handle the asynchronous result of the validation process.
3. An object `validationResults` is created to store the validation results for each field.

Overall, this function performs field validation for a specified route by sending messages to the content windows of the associated `<iframe>` elements and listening for validation results. The Promise is resolved with the validation results when all fields have been validated.

### `FTCaptures.destroy(...)`

This function removes the fields associated with a specified route and destroys any active instances. The function takes one parameter: `routeID` (the ID of the route).

Overall, this function removes the `<iframe>` elements associated with a specified route from the DOM and destroys any active instances associated with that route.