[@fastly/as-fetch](../README.md) / Headers

# Class: Headers

Headers for a [Fetch HTTP Request/Response](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch#Headers).

## Table of contents

### Constructors

- [constructor](headers.md#constructor)

### Methods

- [\_headerNameToLowercase](headers.md#_headernametolowercase)
- [append](headers.md#append)
- [delete](headers.md#delete)
- [get](headers.md#get)
- [has](headers.md#has)
- [keys](headers.md#keys)
- [set](headers.md#set)
- [values](headers.md#values)

## Constructors

### constructor

• **new Headers**()

## Methods

### \_headerNameToLowercase

▸ `Private` **_headerNameToLowercase**(`name`): `string`

#### Parameters

| Name | Type |
| :------ | :------ |
| `name` | `string` |

#### Returns

`string`

___

### append

▸ **append**(`name`, `value`): `void`

Append a header value to a given name.

#### Parameters

| Name | Type | Description |
| :------ | :------ | :------ |
| `name` | `string` | The name of the HTTP header to set. |
| `value` | `string` | The value of the HTTP header to set. |

#### Returns

`void`

___

### delete

▸ **delete**(`name`): `void`

Remove a header from from the `Header` instance.

#### Parameters

| Name | Type | Description |
| :------ | :------ | :------ |
| `name` | `string` | The name of the HTTP header you want to remove from the `Header` instance. |

#### Returns

`void`

___

### get

▸ **get**(`name`): ``null`` \| `string`

Get the value of a header by it's name.

#### Parameters

| Name | Type | Description |
| :------ | :------ | :------ |
| `name` | `string` | string of the name of the header value you would want. |

#### Returns

``null`` \| `string`

the value associated with the header name if it exists.

___

### has

▸ **has**(`name`): `boolean`

Checks for header name existance.

#### Parameters

| Name | Type | Description |
| :------ | :------ | :------ |
| `name` | `string` | The name of the HTTP header you want to know if exists on the headers instance. |

#### Returns

`boolean`

a boolean of whether or not the header exists.

___

### keys

▸ **keys**(): `string`[]

Get all of the `Header` instance's names/keys.

#### Returns

`string`[]

an `Array` of `string`s containing all of the names/keys on the `Header` instance.

___

### set

▸ **set**(`name`, `value`): `void`

Set or Override a header of a given name.

#### Parameters

| Name | Type | Description |
| :------ | :------ | :------ |
| `name` | `string` | The name of the HTTP header to set. |
| `value` | `string` | The value of the HTTP header to set. |

#### Returns

`void`

___

### values

▸ **values**(): `string`[][]

Get all of the `Header` instance's values.

#### Returns

`string`[][]

an `Array` of `Array` of `string`s containing all of the values for each name on a `Header` instance.