init

.gitignore

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+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+.pnpm-debug.log*
+
+# Diagnostic reports (https://nodejs.org/api/report.html)
+report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+*.lcov
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (https://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (https://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directories
+node_modules/
+jspm_packages/
+
+# Snowpack dependency directory (https://snowpack.dev/)
+web_modules/
+
+# TypeScript cache
+*.tsbuildinfo
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Optional stylelint cache
+.stylelintcache
+
+# Microbundle cache
+.rpt2_cache/
+.rts2_cache_cjs/
+.rts2_cache_es/
+.rts2_cache_umd/
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# dotenv environment variable files
+.env
+.env.development.local
+.env.test.local
+.env.production.local
+.env.local
+
+# parcel-bundler cache (https://parceljs.org/)
+.cache
+.parcel-cache
+
+# Next.js build output
+.next
+out
+
+# Nuxt.js build / generate output
+.nuxt
+dist
+
+# Gatsby files
+.cache/
+# Comment in the public line in if your project uses Gatsby and not Next.js
+# https://nextjs.org/blog/next-9-1#public-directory-support
+# public
+
+# vuepress build output
+.vuepress/dist
+
+# vuepress v2.x temp and cache directory
+.temp
+.cache
+
+# Docusaurus cache and generated files
+.docusaurus
+
+# Serverless directories
+.serverless/
+
+# FuseBox cache
+.fusebox/
+
+# DynamoDB Local files
+.dynamodb/
+
+# TernJS port file
+.tern-port
+
+# Stores VSCode versions used for testing VSCode extensions
+.vscode-test
+
+# yarn v2
+.yarn/cache
+.yarn/unplugged
+.yarn/build-state.yml
+.yarn/install-state.gz
+.pnp.*

index.js

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+const express = require('express');
+const { ethers } = require('ethers');
+
+const app = express();
+app.use(express.json());
+
+const PORT = process.env.PORT || 2015;
+
+// Connect to an Ethereum provider
+const provider = new ethers.JsonRpcProvider(process.env.INFURA_URL || 'https://mainnet.infura.io/v3/25c9f1810f234c278a4f13736a897836');
+
+// ERC-20 token contract address
+const tokenAddress = '0x22b6c31c2beb8f2d0d5373146eed41ab9ede3caf';
+
+// ERC-20 token ABI (Application Binary Interface)
+const tokenABI = [
+  // Only the part of the ABI we need: balanceOf and decimals
+  "function balanceOf(address owner) view returns (uint256)",
+  "function decimals() view returns (uint8)"
+];
+
+// Create a contract instance
+const tokenContract = new ethers.Contract(tokenAddress, tokenABI, provider);
+
+app.listen(PORT, () => {
+  console.log("started listening on localhost:" + PORT);
+});
+
+app.get("/status", (request, response) => {
+  const status = {
+    "Status": "Running"
+  };
+
+  response.send(status);
+});
+
+/* ------------------------------------------------------------------------------- */
+
+app.get("/getBalance", async (request, response) => {
+  try {
+    const { address } = request.query;
+
+    if (!address) {
+      return response.status(400).json({ error: "Missing wallet address in the query parameters" });
+    }
+
+    // Check if the provided address is a valid Ethereum address
+    if (!ethers.isAddress(address)) {
+      return response.status(400).json({ error: "Invalid Ethereum address" });
+    }
+
+    // Get the token balance of the wallet address
+    const balanceRaw = await tokenContract.balanceOf(address);
+
+    // Get the number of decimals used by the token
+    const decimals = await tokenContract.decimals();
+
+    // Convert the balance to a human-readable format
+    const balance = ethers.formatUnits(balanceRaw, decimals);
+
+    response.json({ address, tokenAddress, balance});
+  } catch (error) {
+    console.error("Error fetching token balance:", error);
+    response.status(500).json({ error: "Failed to fetch token balance", trace: error });
+  }
+});
+
+

package.json

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+{
+  "name": "web3test",
+  "version": "1.0.0",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "start": "node index.js"
+  },
+  "author": "",
+  "license": "ISC",
+  "description": "",
+  "dependencies": {
+    "ethers": "^6.13.2",
+    "express": "^4.19.2",
+    "web3": "^4.11.1"
+  }
+}