# API client methods

The API clients each expose the following configuration and utility methods you can use to customize your instance.

## addRequestInterceptor

div
code
strong
addRequestInterceptor
({
span
thenDelegate
, 
span
catchDelegate
span
opt
})
Adds a request interceptor to the current API instance. Wrapped around Axios' request interceptor.

**Example**


```js
api.addRequestInterceptor({
  thenDelegate: (config) => {
    config.params['extra-query-param'] = 'foobar';
    return config;
  },
});
```

**Parameters**

| Name  | Type  | Attribute  | Description |
|  --- | --- | --- | --- |
| `thenDelegate`
 | `Function`
 | —
 | Defines the delegate logic to execute when the request is completed. Receives the request configuration as a parameter. Must return the configuration for the request chain to continue. 
`:::js thenDelegate(config) => {Object}` 

**Parameters**
| Name  | Type | Description |
|  --- | --- | --- |
| `config` | Object | The request configuration. Must be returned after being modified. |

 |
| `catchDelegate`
 | `Function`
 | `Optional`
 | Defines a callback to execute before the catch block of the request is executed for this interceptor. 
`:::js catchDelegate(error) => Promise` 

**Parameters**
| Name  | Type | Description |
|  --- | --- | --- |
| `error` | Object | The request error. Should be resolved as a Promise. This method can be used to prevent certain errors from being caught. |

 |


### removeRequestInterceptor

div
code
strong
removeRequestInterceptor
(
span
interceptor
)
Removes a specific request interceptor from the current API instance.

**Example**


```js
// set reference to interceptor
const interceptor = api.addRequestInterceptor({
  thenDelegate: (config) => {
    config.params['extra-query-param'] = 'foobar';
    return config;
  },
});
// remove via reference
api.removeRequestInterceptor(interceptor);
```

**Parameters**

| Name | Type | Attribute | Description |
|  --- | --- | --- | --- |
| interceptor | Function | - | The reference to the previously added request interceptor that should be removed from the current instance. |


### addResponseInterceptor

div
code
strong
addResponseInterceptor
({
span
thenDelegate
, 
span
catchDelegate
span
opt
})
Adds a response interceptor to the current API instance. Wrapped around Axios' response interceptor.

**Example**


```js
api.addResponseInterceptor({
  thenDelegate: (response) => {
    // modify reponse data before having it processed by the API client
    response.data.shift(); //removed first element
    return response;
  },
});
```

**Parameters**

| Name  | Type  | Attribute  | Description |
|  --- | --- | --- | --- |
| `thenDelegate`
 | `Function`
 | —
 | Defines the delegate logic to execute when the request is completed. Receives the API response as a parameter. Must return the response chain to continue. 
`:::js thenDelegate(config) => {Object}` 

**Parameters**
| Name  | Type | Description |
|  --- | --- | --- |
| `response` | Object | The API response. Must be returned after being modified. |

 |
| `catchDelegate`
 | `Function`
 | `Optional`
 | Defines a callback to execute before the catch block of the response is executed for this interceptor. 
`:::js catchDelegate(error) => Promise` 

**Parameters**
| Name  | Type | Description |
|  --- | --- | --- |
| `error` | Object | The response error. Should be resolved as a Promise. This method can be used to prevent certain errors from being caught. |

 |


### removeResponseInterceptor

div
code
strong
removeResponseInterceptor
(
span
interceptor
)
Removes a specific response interceptor from the current API instance.

**Example**


```js
// set reference to interceptor
const interceptor = api.addResponseInterceptor({
  thenDelegate: (response) => {
    response.data.shift();
    return config;
  },
});
// remove via reference
api.removeResponseInterceptor(interceptor);
```

**Parameters**

| Name | Type | Attribute | Description |
|  --- | --- | --- | --- |
| interceptor | Function | - | The reference to the previously added response interceptor that should be removed from the current instance. |


## setTimeout

div
code
strong
setTimeout
(
span
timeout
)
Define the default timeout delay in milliseconds for the current API instance.

**Example**


```js
api.setTimeout(10000);
```

**Parameters**

| Name | Type | Attribute | Description |
|  --- | --- | --- | --- |
| timeout | number | - | Timeout delay in milliseconds. |


## setSessionToken

div
code
strong
setSessionToken
(
span
token
)
Use a JWT session token to identify the API requests. This removes the private API key header if present. This method of authentication should be applied instead of the *private API key* when the client is used in a browser.

To retrieve a session token, first initialize the API client without an API key and use the sign in resource to login the user to Rebilly. The token will be available in the response fields.

For example usage, see the `Usage with JWT` sections in each API client above.

## setEndpoints

div
code
strong
setEndpoints
({
span
live
span
opt
, 
span
sandbox
span
opt
})
Update the endpoints URL for live, sandbox or both mode in the current API instance's active URL. This is useful for testing a different version of the API.

> **Securing communications**
When modifying the API endpoints always use **HTTPS** for a production environment.


**Example**


```js
api.setEndpoints({ live: 'https://api.rebilly.com/experimental/version/url' });
```

**Parameters**

| Name | Type | Attribute | Description |
|  --- | --- | --- | --- |
| live | string | optional | URL for the live API mode. |
| sandbox | string | optional | URL for the sandbox API mode. |


## setProxyAgent

div
code
strong
setProxyAgent
({
span
host
, 
span
port
, 
span
auth
})
Define a proxy for the current API instance. Authorized using **HTTP Basic** credentials.

**Example**


```js
const config = {
  host: '127.0.0.1',
  port: 9000,
  auth: {
    // HTTP Basic
    username: 'foobar',
    password: 'fuubar',
  },
};
// all subsequent API requests will pass through the proxy
api.setProxyAgent(config);
```

**Parameters**

| Name | Type | Attribute | Description |
|  --- | --- | --- | --- |
| `host` | String | — | Hostname of the proxy server. |
| `port` | Number | — | Port of the proxy server. |
| `auth`
 | Object
 | —
 | Basic credentials to connect to the proxy server.

**Properties**
| Name  | Type | Description |
|  --- | --- | --- |
| `username` | String | The username required for basic authentication. |
| `password` | String | The password required for basic authentication. |

 |