eCash

— <a href="https://twitter.com/bytesofman" rel="noopener noreferrer nofollow">Joey</a>, lead dev, CashtabLast month, I wrote about <a href="https://e.cash/blog/building-on-ecash-2022-12" rel="noopener noreferrer nofollow">available tools and libraries for developers</a> looking to get started with eCash. This month, let’s put together a quick demo app using the chronik indexer.Here are some basic bash command prompt instructions. You will need <a href="https://github.com/nvm-sh/nvm" rel="noopener noreferrer nofollow">nodejs</a> to follow the example here.First, we create the directory for our app, initialize an npm module, install chronik, and create our first script.<img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/810141afc24c46d98bb2e39870426f40.jpg" />Next, let&#39;s write a function that queries chronik for information about a transaction.<img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/75d10cdac0fb44f1bc431caaf98052e7.jpg" />Now we can run the script from the command line by entering a txid as an env variable.<img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/8cdd3b1b57c44178a64f6192871eba71.jpg" />Great! Now we can use this script to get tx details for any given txid.What else can we do with chronik?To build a basic wallet app, you need to know how much eCash is available to spend at the wallet&#39;s address. Spendable eCash is stored in objects called &#34;utxos,&#34; or &#34;unspent transaction outputs.&#34; Let’s write a simple script to get utxos from a wallet:<img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/c1da535320cb42ebbc3e1e155738a8ef.jpg" /><img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/3b9ff8e0e9ea48afbb2c5e3b51a42a7d.jpg" />While we are used to thinking of wallets and addresses, chronik accesses information about an address at a lower level. So, for a typical wallet address, we’ll need to first get the hash160 before we can see its utxo set. Let&#39;s write a helper function to get the hash160 from an eCash address.<img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/e01affb7c29e4dba8acd49f26d55395e.jpg" /><img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/ce18b935217e449fb33f179a6892b138.jpg" />Now we can go back and include the helper function addressToHash160 in getUtxosFromAddress.js<img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/a2b5253bb4634370a59accb2cc1087c0.jpg" />...so now, we can get the utxo set of an eCash address by running this script from the command line.<img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/09d30212087e4da9972f1af28219ca4f.jpg" />Great! What about tx history?<img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/4124d7febd3741d6afa9f53ee96465b2.jpg" /><img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/7efcf8ebe14f4d359c3a44042061adae.jpg" /><img src="https://academy-public.coinmarketcap.com/srd-optimized-uploads/6639adad9ec24584a209f07370710732.jpg" />The final app is available <a href="https://github.com/BytesOfMan/chronik-node-testdrive" rel="noopener noreferrer nofollow">here.</a> You could also check out <a href="https://github.com/Bitcoin-ABC/bitcoin-abc/tree/master/web/cashtab" rel="noopener noreferrer nofollow">Cashtab&#39;s source code</a> to see how to use chronik in a React app. Or check out the <a href="https://t.me/eCashDevelopment" rel="noopener noreferrer nofollow">eCash development telegram chat</a> if you have any questions about using these tools to build on eCash.Originally Published: <a href="https://e.cash/blog/building-on-ecash-january-2023" rel="noopener noreferrer nofollow">Building on eCash: Creating a Demo App Using the Chronik Indexer</a>

Building on eCash: Creating a Demo App Using the Chronik Indexer

eCash

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