> ## Documentation Index
> Fetch the complete documentation index at: https://wreq.sqdsh.win/llms.txt
> Use this file to discover all available pages before exploring further.

# Utilities

> Utility functions for browser profiles and configuration.

## getProfiles()

Get a list of all available browser profile labels.

### Signature

```typescript theme={null}
function getProfiles(): BrowserProfile[]
```

### Returns

Array of profile names that can be used with the `browser` option.

### Example

```typescript theme={null}
import { getProfiles } from 'wreq-js';

const profiles = getProfiles();
console.log(profiles);
// Example output: ['chrome_142', 'firefox_139', 'safari_18', ...]
```

### Using a random profile

```typescript theme={null}
import { fetch, getProfiles } from 'wreq-js';

const profiles = getProfiles();
const randomProfile = profiles[Math.floor(Math.random() * profiles.length)];

const response = await fetch('https://example.com', {
  browser: randomProfile,
});
```

***

## getOperatingSystems()

Get a list of all available operating systems for emulation.

### Signature

```typescript theme={null}
function getOperatingSystems(): EmulationOS[]
```

### Returns

Array of OS names that can be used with the `os` option.

### Example

```typescript theme={null}
import { getOperatingSystems } from 'wreq-js';

const systems = getOperatingSystems();
console.log(systems);
// Example output: ['windows', 'macos', 'linux', 'android', 'ios']
```

### Combining browser and OS

```typescript theme={null}
import { fetch, getProfiles, getOperatingSystems } from 'wreq-js';

// Chrome on Windows
const response = await fetch('https://example.com', {
  browser: 'chrome_142',
  os: 'windows',
});

// Safari on iOS
const mobileResponse = await fetch('https://example.com', {
  browser: 'safari_18',
  os: 'ios',
});
```

***

## resolveProfile()

Resolve a browser family alias to the concrete profile it points at.

### Signature

```typescript theme={null}
function resolveProfile(browser: BrowserProfile | BrowserAlias): BrowserProfile
```

### Returns

The concrete profile. Concrete profiles pass through unchanged, so this is safe to call on
any value accepted by the `browser` option.

### Example

```typescript theme={null}
import { resolveProfile } from 'wreq-js';

resolveProfile('firefox');     // 'firefox_149'
resolveProfile('firefox_143'); // 'firefox_143'
```

An alias resolves against the profile set shipped with your installed version of wreq-js,
so the result moves when you upgrade. Log it when you need to know which fingerprint a
given run actually used.

***

## getEmulationHeaders()

Get the headers a browser profile injects into every request, without sending one.

### Signature

```typescript theme={null}
function getEmulationHeaders(browser?: BrowserProfile, os?: EmulationOS): Headers
```

Both arguments default to the same profile and OS as [`fetch`](/api-reference/fetch).

### Returns

A `Headers` instance holding the profile's headers, in the profile's own order and casing.

Transport-level headers are not included: `Host`, `Connection`, `Content-Length`, and
`Accept-Encoding` are added per request rather than by the emulation profile.

### Example

```typescript theme={null}
import { getEmulationHeaders } from 'wreq-js';

const defaults = getEmulationHeaders('firefox_147');
console.log(defaults.get('user-agent'));
// Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:147.0) Gecko/20100101 Firefox/147.0
```

### Reusing a profile's User-Agent

Passing a header through `headers` replaces the profile's matching header and leaves the
rest of the fingerprint intact, so read the value first when you want to build on it.

```typescript theme={null}
import { fetch, getEmulationHeaders } from 'wreq-js';

const userAgent = getEmulationHeaders('firefox_147', 'windows').get('user-agent');

const response = await fetch('https://example.com', {
  browser: 'firefox_147',
  os: 'windows',
  headers: { 'X-Forwarded-User-Agent': userAgent ?? '' },
});
```

***

## Headers

The `Headers` class for working with HTTP headers.

### Constructor

```typescript theme={null}
declare class Headers {
  constructor(init?: HeadersInit);
}
```

### Methods

* `append(name, value)`: add a header value
* `delete(name)`: remove a header
* `get(name)`: get a header value
* `has(name)`: check if header exists
* `set(name, value)`: set a header value
* `entries()`: iterate over header entries
* `keys()`: iterate over header names
* `values()`: iterate over header values

### Example

```typescript theme={null}
import { fetch, Headers } from 'wreq-js';

const headers = new Headers();
headers.set('Authorization', 'Bearer token');
headers.set('Content-Type', 'application/json');

const response = await fetch('https://api.example.com', {
  browser: 'chrome_142',
  headers,
});
```

***

## Response

The `Response` class representing HTTP responses.

### Properties

* `status`: HTTP status code
* `statusText`: HTTP status text
* `headers`: response headers
* `ok`: `true` if status is 200-299
* `url`: final URL after redirects
* `redirected`: `true` if the response is the result of a redirect
* `body`: `ReadableStream<Uint8Array>` or `null`
* `bodyUsed`: `true` if body has been read
* `contentLength`: content length from headers, or `null`
* `cookies`: parsed response cookies as `Record<string, string | string[]>`

### Methods

* `json()`: parse body as JSON
* `text()`: get body as string
* `arrayBuffer()`: get body as ArrayBuffer
* `bytes()`: get body as Uint8Array
* `blob()`: get body as Blob
* `formData()`: parse body as FormData
* `clone()`: clone the response