[Examples] Add pagination JS ESM Node example

Author: sebastianquek

examples/node/pagination_js_esm/.env.example

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+API_KEY=YOUR_API_KEY

examples/node/pagination_js_esm/README.md

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+# Node.js pagination JavaScript (ESM) example
+
+## Usage
+
+1. Build module
+
+```bash
+cd ../../../   # Navigate to the root folder
+deno task npm
+```
+
+2. Setup environment variables
+
+- Duplicate `.env.example` and name it `.env`.
+- Replace `YOUR_API_KEY` with your SerpApi API key.
+
+3. Install dependencies and run example
+
+```bash
+cd examples/node/pagination_js_esm
+npm i
+npm start
+```
+
+## Notes
+
+- If you want to run the example without building the module, you can update
+  `package.json` to depend on the published `serpapi` npm module instead:
+  ```json
+  {
+    "type": "module",
+    "dependencies": {
+      "dotenv": "*",
+      "serpapi": "*" // Relies on the npm module
+    },
+    "scripts": {
+      "start": "node example.js"
+    }
+  }
+  ```

examples/node/pagination_js_esm/example.js

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+import * as Dotenv from "dotenv";
+import { config, getJson } from "serpapi";
+
+Dotenv.config();
+const apiKey = process.env.API_KEY;
+
+const extractLinks = (results) => results.map((r) => r.link);
+
+const params = {
+  q: "Coffee",
+  api_key: apiKey,
+};
+
+// Pagination (async/await)
+let page1 = await getJson("google", params);
+console.log(
+  "First page links",
+  extractLinks(page1.organic_results),
+);
+let page2 = await page1.next?.();
+console.log(
+  "Second page links",
+  extractLinks(page2?.organic_results),
+);
+
+// Pagination (callback)
+getJson("google", params, (page1) => {
+  console.log(
+    "First page links",
+    extractLinks(page1.organic_results),
+  );
+  page1.next?.((page2) => {
+    console.log(
+      "Second page links",
+      extractLinks(page2.organic_results),
+    );
+  });
+});
+
+// Use global config
+config.api_key = apiKey;
+page1 = await getJson("google", { q: "Coffee" });
+page2 = await page1.next?.();
+console.log(
+  "Second page links",
+  extractLinks(page2?.organic_results),
+);
+
+// Pagination loop (async/await)
+let links = [];
+let page = await getJson("google", { q: "Coffee" });
+while (page) {
+  links.push(...extractLinks(page.organic_results));
+  if (links.length >= 30) break;
+  page = await page.next?.();
+}
+console.log(links);
+
+// Pagination loop (callback)
+links = [];
+getJson("google", { q: "Coffee" }, (page) => {
+  links.push(...extractLinks(page.organic_results));
+  if (links.length < 30 && page.next) {
+    page.next();
+  } else {
+    console.log(links);
+  }
+});

examples/node/pagination_js_esm/package-lock.json

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+{
+  "type": "module",
+  "dependencies": {
+    "dotenv": "*",
+    "serpapi": "../../../npm"
+  },
+  "scripts": {
+    "start": "node example.js"
+  }
+}