example usage and doc cleanup

Author: Jayant Krishnamurthy

README.md

@@ -24,25 +24,27 @@ $ yarn add @pythnetwork/client
 
 ## Example Usage
 
-This library provides a subscription model for consuming all price updates:
+This library provides a subscription model for consuming price updates:
 
 ```javascript
-import { Connection, PublicKey } from '@solana/web3.js'
-import { parseMappingData, parsePriceData, parseProductData } from '@pythnetwork/client'
-import { getPythProgramKeyForCluster } from '@pythnetwork/client'
-
-const connection = new Connection(SOLANA_CLUSTER_URL)
-const pythPublicKey = getPythProgramKeyForCluster(CLUSTER)
-
-const pythConnection = new PythConnection(connection, pythPublicKey) 
+const pythConnection = new PythConnection(solanaWeb3Connection, getPythProgramKeyForCluster(solanaClusterName))
 pythConnection.onPriceChange((product, price) => {
   // sample output:
   // SRM/USD: $8.68725 ±$0.0131
   console.log(`${product.symbol}: $${price.price} \xB1$${price.confidence}`)
 })
 
+// Start listening for price change events.
 pythConnection.start()
 ```
 
+The `onPriceChange` callback will be invoked every time a Pyth price gets updated.
+This callback gets two arguments:
+* `price` contains the official Pyth price and confidence, along with the component prices that were combined to produce this result.
+* `product` contains metadata about the price feed, such as the symbol (e.g., "BTC/USD") and the number of decimal points.
+
+See `src/example_usage.ts` for a runnable example of the above usage.
+You can run this example with `npm run example`.
+
 You may also register to specific account updates using `connection.onAccountChange` in the solana web3 API, then
 use the methods in `index.ts` to parse the on-chain data structures into Javascript-friendly objects.

package-lock.json

@@ -18,7 +18,8 @@
     "prepublishOnly": "npm test && npm run lint",
     "preversion": "npm run lint",
     "version": "npm run format && git add -A src",
-    "postversion": "git push && git push --tags"
+    "postversion": "git push && git push --tags",
+    "example": "npm run build && node lib/example_usage.js"
   },
   "keywords": [
     "pyth",

package.json

@@ -0,0 +1,17 @@
+import {Cluster, clusterApiUrl, Connection, PublicKey} from '@solana/web3.js'
+import { PythConnection } from './PythConnection'
+import { getPythProgramKeyForCluster } from './cluster'
+
+const SOLANA_CLUSTER_NAME: Cluster = 'devnet'
+const connection = new Connection(clusterApiUrl(SOLANA_CLUSTER_NAME))
+const pythPublicKey = getPythProgramKeyForCluster(SOLANA_CLUSTER_NAME)
+
+const pythConnection = new PythConnection(connection, pythPublicKey)
+pythConnection.onPriceChange((product, price) => {
+  // sample output:
+  // SRM/USD: $8.68725 ±$0.0131
+  console.log(`${product.symbol}: $${price.price} \xB1$${price.confidence}`)
+})
+
+console.log("Reading from Pyth price feed...")
+pythConnection.start()

src/example_usage.ts

@@ -11,7 +11,7 @@ export const PriceStatus = ['Unknown', 'Trading', 'Halted', 'Auction']
 export const CorpAction = ['NoCorpAct']
 export const PriceType = ['Unknown', 'Price']
 export const DeriveType = ['Unknown', 'TWAP', 'Volatility']
-export const AccountType = ['Mapping', 'Product', 'Price', 'Test']
+export const AccountType = ['Unknown', 'Mapping', 'Product', 'Price', 'Test']
 
 /** Number of slots that can pass before a publisher's price is no longer included in the aggregate. */
 export const MAX_SLOT_DIFFERENCE = 25