Support async iteration

README.md

@@ -77,16 +77,18 @@ fs.createReadStream('path/to/archive.zip')
   });
 ```
 
-and the same example using async iterators:
+and the same example using async iterators on node v12 and above:
 
 ```js
 const zip = fs.createReadStream('path/to/archive.zip').pipe(unzipper.Parse({forceStream: true}));
-for await (const entry of zip) {
+for await (const entry of unzipper.iterateStream(zip)) {
   const fileName = entry.path;
   const type = entry.type; // 'Directory' or 'File'
   const size = entry.vars.uncompressedSize; // There is also compressedSize;
   if (fileName === "this IS the file I'm looking for") {
-    entry.pipe(fs.createWriteStream('output/path'));
+    for await (const chunk of unzipper.iterateStream(entry)) {
+      console.log(chunk);
+    }
   } else {
     entry.autodrain();
   }

lib/iterateStream.js

@@ -0,0 +1,35 @@
+const {once} = require('events');
+
+module.exports = async function* iterateStream(stream) {
+  const contents = [];
+  stream.on('data', data => contents.push(data));
+
+  let resolveStreamEndedPromise;
+  const streamEndedPromise = new Promise(resolve => (resolveStreamEndedPromise = resolve));
+
+  let ended = false;
+  stream.on('end', () => {
+    ended = true;
+    resolveStreamEndedPromise();
+  });
+
+  let error = false;
+  stream.on('error', err => {
+    error = err;
+    resolveStreamEndedPromise();
+  });
+
+  while (!ended || contents.length > 0) {
+    if (contents.length === 0) {
+      stream.resume();
+      // eslint-disable-next-line no-await-in-loop
+      await Promise.race([once(stream, 'data'), streamEndedPromise]);
+    } else {
+      stream.pause();
+      const data = contents.shift();
+      yield data;
+    }
+    if (error) throw error;
+  }
+  resolveStreamEndedPromise();
+};

unzip.js

@@ -8,4 +8,8 @@ require('setimmediate');
 exports.Parse = require('./lib/parse');
 exports.ParseOne = require('./lib/parseOne');
 exports.Extract = require('./lib/extract');
-exports.Open = require('./lib/Open');
+exports.Open = require('./lib/Open');
+
+if (parseInt(process.versions.node.split('.')[0], 10) >= 12) {
+  exports.iterateStream = require('./lib/iterateStream');
+}