> For the complete documentation index, see [llms.txt](https://docs.ternoa.network/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ternoa.network/build-1/javascript/nft-features-and-pallets/sale-your-nft/auction/create-an-english-auction.md).

# Create an English auction

### Prerequisites

Before getting started, make sure you have the following ready:

1. [Create a Ternoa](/getting-started/wallets/ternoa-wallet.md) account with [Alphanet CAPS](broken://pages/ej9gceaLIhCN2PgUBh42)
2. Install and set up your editor of choice (we will use Visual Studio Code \[VSC] in this tutorial)
3. Install [NodeJS v.14+](https://nodejs.org/en/download/) & NPM
4. [Install & initialize Ternoa-JS](/build-1/javascript/ternoa-js-library-utilities/installation-and-initialization.md)

### Create an auction on a marketplace using Ternoa-JS

This function puts an existing NFT to auction on a marketplace on the Ternoa chain. It returns an object promise containing the AuctionCreatedEvent provided by the Ternoa blockchain.

{% hint style="info" %}
Use your own account by updating the `//TernoaTestAccount` with your account seed when retrieving the keyring from the example below. **Replace the NFT\_ID** with the existing one to auction, the **MARKETPLACE\_ID** by the existing marketplace id you want the NFT to be auctioned on, the **startBlock**, **endBlock**, **startPrice**, **buyItPrice**. 
{% endhint %}

```typescript
import {
    createAuction,
    initializeApi,
    getKeyringFromSeed,
    WaitUntil,
} from "ternoa-js";

const listAuctionNFT = async () => {
    try {
        await initializeApi();
        const keyring = await getKeyringFromSeed("//TernoaTestAccount");
        const NFT_ID = // update with the nft id you want to auction.
        const MARKETPLACE_ID = // update with the marketplace id you want the NFT to be auctioned on.
        const startBlock = // update with the auction start block number.
        const endBlock = // update with the auction end block number.
        const startPrice = // update with the auction start price.
        const buyItPrice = // update with the auction "buy it now" price.
        const res = await createAuction(
            NFT_ID,
            MARKETPLACE_ID,
            startBlock,
            endBlock,
            startPrice,
            buyItPrice,
            keyring,
            WaitUntil.BlockInclusion
        );
        console.log(`NFT id: ${res.nftId} auctioned on marketplace ${res.marketplaceId} for ${res.startPrice}CAPS`);
    } catch (e) {
        console.error(e);
    }
};
```

#### The expected params

```markdown
`nftId`: The ID of the NFT.
`marketplaceId`: The ID of the marketplace where the auction will take place.
`startBlock`: The ID of the block at which the auction starts.
`endBlock`: The ID of the block at which the auction ends.
`startPrice`: The price at which the auction starts.
`buyItPrice`: The price to directly buy the NFT before the auction starts. Optional Parameter.
`keyring`: The provided keyring (containing the address) will be used to sign the transaction and pay the execution fee.
`waitUntil`: WaitUntil defines at which point we want to get the results of the transaction execution: BlockInclusion or BlockFinalization.
```

#### Response

The response provided from the blockchain event includes all the information below according to the parameters provided when buying an NFT.

```markdown
`nftId`: NFT id auctioned.
`marketplaceId`: Marketplace id where the NFT was listed for auction.
`creator`: The auction creator.
`startPrice`: The starting auction price of the NFT as a string corresponding to the value in a big number.
`startPriceRounded`: The starting auction price of the NFT as a number.
`buyItPrice`: If set, the price to directly buy the NFT before the auction starts as a string corresponding to the value in a big number.
`buyItPriceRounded`: If set, The price to directly buy the NFT before the auction starts as a number.
`startBlock`: The auction starting block number.
`endBlock`: The auction ending block number.
```

### Support

If you face any trouble, feel free to reach out to our community engineers in our [Discord](https://discord.gg/fUmBkPpnRu).