docs(examples): adds new example to repo (#621)

* docs(examples): adds new example to repo

Creates a new example in the repository that demonstrates how to use the
Ethereum Attestation Service with a Defender Relay Signer

* style(imports): use default import of node:process pkg

Use default import of node:process instead of only importing env method

examples/eas-relayer-signer/package.json

@@ -0,0 +1,23 @@
+{
+	"name": "@openzeppelin/defender-sdk-example-eas-relay-signer",
+	"version": "1.15.2",
+	"private": true,
+	"main": "index.js",
+	"type": "module",
+	"scripts": {
+		"build": "tsc",
+		"start": "node dist/index.js"
+	},
+	"author": "OpenZeppelin Defender <[email protected]>",
+	"license": "MIT",
+	"description": "An example of using the Ethereum Attestation Service with a Defender Relay Signer",
+	"devDependencies": {
+		"typescript": "^5.6.3"
+	},
+	"dependencies": {
+		"@ethereum-attestation-service/eas-sdk": "^2.7.0",
+		"@openzeppelin/defender-sdk": "1.15.2",
+		"dotenv": "^16.4.5",
+		"ethers": "^6.13.4"
+	}
+}

examples/eas-relayer-signer/src/index.ts

@@ -0,0 +1,57 @@
+import { EAS, NO_EXPIRATION, SchemaEncoder, TransactionSigner } from '@ethereum-attestation-service/eas-sdk';
+
+import dotenv from 'dotenv';
+dotenv.config();
+import { Agent } from 'node:https';
+import process from 'node:process';
+
+import { Defender, DefenderOptions } from '@openzeppelin/defender-sdk';
+import { TypeDataSigner } from '@ethereum-attestation-service/eas-sdk/dist/offchain/typed-data-handler.js';
+
+export const EASContractAddress = '0xC2679fBD37d54388Ce493F1DB75320D236e1815e'; // Sepolia v0.26
+
+const creds = {
+  relayerApiKey: process.env.RELAYER_API_KEY,
+  relayerApiSecret: process.env.RELAYER_API_SECRET,
+  //optional https config to keep connection alive. You can pass any configs that are accepted by https.Agent
+  httpsAgent: new Agent({ keepAlive: true }),
+};
+
+const validForSeconds = 60 * 60 * 24;
+const client = new Defender(creds as DefenderOptions);
+const provider = client.relaySigner.getProvider({ ethersVersion: 'v6' });
+const signer = await client.relaySigner.getSigner(provider, {
+  speed: 'fast',
+  validForSeconds,
+  ethersVersion: 'v6',
+});
+
+// Initialize EAS with the EAS contract address on whichever chain where your schema is defined
+const eas = new EAS(EASContractAddress);
+eas.connect(provider as unknown as TransactionSigner);
+
+const offchain = await eas.getOffchain();
+
+// Initialize SchemaEncoder with the schema string
+// Note these values are sample values and should be filled with actual values
+// Code samples can be found when viewing each schema on easscan.org
+const schemaEncoder = new SchemaEncoder('uint256 eventId, uint8 voteIndex');
+const encodedData = schemaEncoder.encodeData([
+  { name: 'eventId', value: 1, type: 'uint256' },
+  { name: 'voteIndex', value: 1, type: 'uint8' },
+]);
+
+const offchainAttestation = await offchain.signOffchainAttestation(
+  {
+    recipient: '0xFD50b031E778fAb33DfD2Fc3Ca66a1EeF0652165',
+    expirationTime: NO_EXPIRATION, // Unix timestamp of when attestation expires (0 for no expiration)
+    time: BigInt(Math.floor(Date.now() / 1000)), // Unix timestamp of current time
+    revocable: true, // Be aware that if your schema is not revocable, this MUST be false
+    schema: '0xb16fa048b0d597f5a821747eba64efa4762ee5143e9a80600d0005386edfc995',
+    refUID: '0x0000000000000000000000000000000000000000000000000000000000000000',
+    data: encodedData,
+  },
+  signer as TypeDataSigner,
+);
+
+console.log(offchainAttestation);

examples/eas-relayer-signer/tsconfig.json

@@ -0,0 +1,34 @@
+{
+	"compilerOptions": {
+		/* Language and Environment */
+		"target": "es2022" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,
+
+		/* Modules */
+		"module": "nodenext" /* Specify what module code is generated. */,
+		"rootDir": "src" /* Specify the root folder within your source files. */,
+		"moduleResolution": "nodenext" /* Specify how TypeScript looks up a file from a given module specifier. */,
+		"baseUrl": ".",
+		"resolveJsonModule": true /* Enable importing .json files. */,
+
+		/* JavaScript Support */
+		"allowJs": true /* Allow JavaScript files to be a part of your program. Use the 'checkJS' option to get errors from these files. */,
+
+		/* Emit */
+		"declaration": true /* Generate .d.ts files from TypeScript and JavaScript files in your project. */,
+		"sourceMap": true /* Create source map files for emitted JavaScript files. */,
+		"outDir": "dist" /* Specify an output folder for all emitted files. */,
+		"importHelpers": true /* Allow importing helper functions from tslib once per project, instead of including them per-file. */,
+
+		/* Interop Constraints */
+		"esModuleInterop": true /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */,
+		"forceConsistentCasingInFileNames": true /* Ensure that casing is correct in imports. */,
+
+		/* Type Checking */
+		"strict": true /* Enable all strict type-checking options. */,
+
+		/* Completeness */
+		"skipLibCheck": true /* Skip type checking all .d.ts files. */
+	},
+	"include": ["src/**/*"],
+	"exclude": ["dist", "node_modules"]
+}