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How to buy an NFT on a marketplace on-chain

Prerequisites​

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

  1. Create a Ternoa account with Alphanet CAPS
  2. Install and set up your editor of choice (we will use Visual Studio Code [VSC] in this tutorial)
  3. Install NodeJS v.14+ & NPM
  4. Install & initialize Ternoa-JS

Buy an NFT on a marketplace using Ternoa-JS​

This function buys a listed-for-sale NFT on a marketplace on the Ternoa chain. It returns an object promise containing the NFTSoldEvent provided by the Ternoa blockchain.

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 listed NFT to buy.

import {
    buyNft,
    initializeApi,
    getKeyringFromSeed,
    WaitUntil,
} from "ternoa-js";

const buyNft = async () => {
    try {
        await initializeApi();
        const keyring = await getKeyringFromSeed("//TernoaTestAccount");
        const NFT_ID = // update with the nft id you want to buy.
        const res = await buyNft(
            NFT_ID,
            keyring,
            WaitUntil.BlockInclusion
        );
        console.log(`NFT id: ${res.nftId} bought for ${res.listedPriceRounded}CAPS on marketplace ${res.marketplaceId}.`);
    } catch (e) {
        console.error(e);
    }
};

The expected params​

`nftId`: NFT Id of the NFT to buy.
`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.

`nftId`: NFT id bought.
`marketplaceId`: Marketplace id where the NFT was listed for sale.
`buyer`: The NFT's new owner.
`listedPrice`: The sale price of the NFT as a string corresponding to the value in a big number.
`listedPriceRounded`: The sale price of the NFT as a number.
`marketplaceCut`: The marketplace commission fee on the NFT sale as a string corresponding to the value in a big number.
`marketplaceCutRounded`: The marketplace commission fee on the NFT sale as a number.
`royaltyCut`: The NFT creator royalty fee on the NFT sale as a string corresponding to the value in a big number.
`royaltyCutRounded`: The NFT creator royalty fee on the NFT sale as a number.

Support​

If you face any trouble, feel free to reach out to our community engineers in our Discord.