---
name: "RequestTask.onHeadersReceived"
mode: "kit"
versionRequirements:
  - { name: "BaseKit", version: "2.0.1" }
platform:
  - "iOS"
  - "Android"
---

## RequestTask.onHeadersReceived

> [VERSION] BaseKit >= 2.0.1

> [PLATFORM] iOS, Android

### Description

Listen for the HTTP Response Header event. Fires earlier than the request completion event

### Parameters

`(listener: Function)`

| Parameter | Type | Required | Default | Description |
| --- | --- | --- | --- | --- |
| `listener` | `(params: Object) => void` | Yes | - | Event listener callback function |

##### RequestTask.onHeadersReceived.listener(params) properties

| Property | Type | Required | Default | Since | Description |
| --- | --- | --- | --- | --- | --- |
| `header` | `Record<string, string>` | Yes | - | `2.0.1` | HTTP Response Headers returned by the developer server |
| `requestId` | `string` | Yes | - | `2.0.1` | Network request ID |


### Examples

#### Demo

```tsx
import { request } from '@ray-js/ray'

// Listen for HTTP response header events (triggered earlier than request completion).
// ty.request returns a RequestTask; register onHeadersReceived on it to be notified when response headers are received.
const task = request({
  url: "https://httpbin.org/get",
  method: "GET",
  success: data => {
    console.log(data);
  },
  fail: error => {
    console.error(error);
  },
});

task.onHeadersReceived(e => {
  console.log("[onHeadersReceived]", e);
});
```