docs: add example to force buffer

Author: GrosSacASac

examples/forceBuffer.js

@@ -0,0 +1,69 @@
+// warning: forcing file into a Buffer elminates the benefits of using streams and may cause memory overflow
+import http from 'node:http';
+import { Buffer } from 'node:buffer'
+import { Writable } from 'node:stream';
+import formidable from '../src/index.js';
+
+
+const server = http.createServer((req, res) => {
+  if (req.url === '/api/upload' && req.method.toLowerCase() === 'post') {
+    // parse a file upload
+    const endBuffers = {};
+    const form = formidable({
+      fileWriteStreamHandler: (file) => {
+        const chunks = [];
+        
+        const writable = new Writable({
+          write (chunk, enc, next) {
+            chunks.push(chunk);            
+            next();
+          },
+          destroy() {
+            endBuffers = {};
+          },
+          final(cb) {
+            const buffer = Buffer.concat(chunks);
+            // if filename option is not provided file.newFilename will be a random string
+            endBuffers[file.newFilename] = buffer;
+            cb();
+          },
+        })
+        return writable;
+      },
+    });
+
+    form.parse(req, (err, fields, files) => {
+      // available here endBuffers
+      if (err) {
+        console.error(err);
+        res.writeHead(err.httpCode || 400, { 'Content-Type': 'text/plain' });
+        res.end(String(err));
+        return;
+      }
+      res.writeHead(200, { 'Content-Type': 'application/json' });
+      res.end(JSON.stringify({ fields, files }, null, 2));
+
+      Object.entries(endBuffers).map(([key, value]) => {
+        console.log(key);
+        console.log(value.toString("utf8"));
+      });
+    });
+
+    return;
+  }
+
+  // show a file upload form
+  res.writeHead(200, { 'Content-Type': 'text/html' });
+  res.end(`
+    <h2>With Node.js <code>"http"</code> module</h2>
+    <form action="/api/upload" enctype="multipart/form-data" method="post">
+      <div>Text field title: <input type="text" name="title"></div>
+      <div>File: <input type="file" name="myfile"></div>
+      <button>Upload</button>
+    </form>
+  `);
+});
+
+server.listen(3000, () => {
+  console.log('Server listening on http://localhost:3000 ...');
+});