Add a way to get lines which didn't parse

README.md

@@ -26,4 +26,31 @@ Will output:
 { hello: 'world' }
 ```
 
-If invalid JSON gets written, it's silently ignored.
+If invalid JSON gets written, it's ignored.
+
+You can listen to 'parsefail' event on the stream to get the lines that failed to parse.
+
+```js
+var JSONStream = require('json-stream');
+
+var stream = JSONStream();
+
+stream.on('data', function (chunk) {
+  console.dir(chunk);
+});
+stream.on('parsefail', function (chunk) {
+  console.dir('!!'+chunk);
+});
+stream.write('{"a":');
+stream.write('42}\n');
+stream.write('{"hel');
+stream.write('lo": "world"}\n');
+stream.write('not json\n');
+```
+
+Will output:
+```
+{ a: 42 }
+{ hello: 'world' }
+!!not json
+```

lib/json-stream.js

@@ -24,10 +24,15 @@ JSONStream.prototype._transform = function (data, encoding, callback) {
   while (++ptr <= data.length) {
     if (data[ptr] === 10 || ptr === data.length) {
       var line;
+      var slice = data.slice(start, ptr)
       try {
-        line = JSON.parse(data.slice(start, ptr));
+        line = JSON.parse(slice);
+      }
+      catch (ex) {
+          if (data[ptr] === 10){
+              this.emit('parsefail', slice)
+          }
       }
-      catch (ex) { }
       if (line) {
         this.push(line);
         line = null;

test/json-stream-test.js

@@ -29,6 +29,22 @@ function expect(stream, events) {
   });
 }
 
+function expectSideEffect(stream, evnetName, events) {
+  var lines = [], endCalled = false;
+  stream.on(evnetName, function (line) {
+    if (line) {
+      lines.push(line.toString());
+    }
+  });
+  stream.on('end', function () {
+    endCalled = true;
+  });
+  process.on('exit', function () {
+    assert.deepEqual(lines, events);
+    assert(endCalled);
+  });
+}
+
 var stream = JSONStream();
 expect(stream, [ { a: 42 } ]);
 write(stream, '{"a": 42}\n');
@@ -37,6 +53,11 @@ stream = JSONStream();
 expect(stream, [ { a: 42 } ]);
 write(stream, '{"a":', '42}\n');
 
+stream = JSONStream();
+expect(stream, [ { a: 42 } ]);
+expectSideEffect(stream, 'parsefail', [ 'blah' ]);
+write(stream, '{"a":', '42}\n','blah\n');
+
 stream = JSONStream();
 expect(stream, [ { a: 42, b: 1337 } ]);
 write(stream, '{"a":', '42', ',"b": 1337', '}\n');