# approve

## Description

The `approve` function allows the owner of an ERC721 token to grant approval to another address or contract to transfer the token on their behalf.

## Parameters

| Parameter         | Type   | Description                                                        |
| ----------------- | ------ | ------------------------------------------------------------------ |
| `blockchain`      | string | The blockchain network to use, e.g., Ethereum, Binance Smart Chain |
| `contractAddress` | string | The address of the ERC721 contract containing the token            |
| `tokenId`         | string | The ID of the token to approve for transfer                        |
| `spender`         | string | The address of the account or contract to grant transfer approval  |
| `privateKey`      | string | The private key of the token owner's account                       |

## Response

| Field     | Type   | Description                                        |
| --------- | ------ | -------------------------------------------------- |
| `code`    | number | 1 for success, 0 for failure                       |
| `receipt` | object | The transaction receipt of the approve transaction |

## Example Request and Response

### Prerequisites

Before making requests with Volary SDK, you must have it installed.

You can install Volary SDK using either **`npm`** or **`yarn`**. Use the following commands to install Volary SDK:

```jsx
npm install @nest25/evm-chains-lib
OR
yarn add @nest25/evm-chains-lib
```

### Request

Here is an example of how to make a `approve` request using the Volary SDK:

```jsx
const {ERC721} = require('@nest25/evm-chains-lib')
// create a new wallet instance
const erc721 = new ERC721();
const privateKey = "your private key here"

const main = async () => {
    // approve erc721 token
    const receipt=await erc721.approve(
        'klay',
        '0xE4eD9066bD1A34994445cAd01Cb9A73A59b8A045',
        '1',
        '0xE668C72D4C67236A712Ce69A91C74358586f31ed',
        privateKey
        )
    // print receipt
    console.log(receipt);
}
main()
```

### Response

```jsx
  
```

## Use Cases

* **Crypto wallets:** They can use this function to grant approval to other addresses or contracts to transfer their ERC721 tokens on their behalf.
* **DApp developers:** Developers can use this function to enable users to grant approval to their smart contracts to transfer their ERC721 tokens.