docs: add example for storing dag-json data using the storeCar me…

…hod (#2402)

examples/client/node.js/storeCar-dagJSON.js

@@ -0,0 +1,31 @@
+import { NFTStorage } from 'nft.storage'
+import { CarWriter } from '@ipld/car'
+import * as dagJSON from '@ipld/dag-json'
+import { sha256 } from 'multiformats/hashes/sha2'
+import { encode } from 'multiformats/block'
+
+const token = 'API_KEY' // your API key from https://nft.storage/manage
+
+async function main() {
+  const storage = new NFTStorage({ token })
+
+  // Encode data to DAG
+  const objToStore = { hello: 'world' }
+  const block = await encode({ value: objToStore, codec: dagJSON, hasher: sha256 })
+
+  // Encode DAG to CAR
+  const { writer, out } = CarWriter.create([block.cid])
+  writer.put(block)
+  writer.close()
+
+  const chunks = []
+  for await (const chunk of out) {
+    chunks.push(chunk)
+  }
+  const car = new Blob(chunks)
+
+  // Store CAR with NFT.Storage
+  await storage.storeCar(car, { decoders: [dagJSON] })
+  console.log(block.cid.toString())
+}
+main()