let join also accumulate strings (and not fail)

nodes/core/logic/17-split.html

@@ -239,6 +239,9 @@
                 var val = $(this).val();
                 $(".node-row-custom").toggle(val==='custom');
                 $(".form-tips-auto").toggle(val==='auto');
+                if (val === "auto") {
+                    $("#node-input-accumulate").attr('checked', false);
+                }
             });
 
             $("#node-input-build").change(function(e) {

nodes/core/logic/17-split.js

@@ -354,9 +354,12 @@ module.exports = function(RED) {
                             currentCount:0,
                             payload:{},
                             targetCount:targetCount,
-                            type:"object",
+                            type:payloadType,
                             msg:msg
                         }
+                        if (payloadType === 'string') {
+                            inflight[partId].payload = [];
+                        }
                     }
                     else {
                         inflight[partId] = {
@@ -364,7 +367,6 @@ module.exports = function(RED) {
                             payload:[],
                             targetCount:targetCount,
                             type:payloadType,
-                            joinChar: joinChar,
                             msg:msg
                         };
                         if (payloadType === 'string') {
@@ -374,7 +376,6 @@ module.exports = function(RED) {
                         } else if (payloadType === 'buffer') {
                             inflight[partId].bufferLen = 0;
                         }
-
                     }
                     if (node.timer > 0) {
                         inflight[partId].timeout = setTimeout(function() {

test/nodes/core/logic/17-split_spec.js

@@ -144,6 +144,27 @@ describe('JOIN node', function() {
         });
     });
 
+    it('should join bits of string back together automatically', function(done) {
+        var flow = [{id:"n1", type:"join", wires:[["n2"]], joiner:",", build:"string", mode:"auto"},
+                    {id:"n2", type:"helper"}];
+        helper.load(joinNode, flow, function() {
+            var n1 = helper.getNode("n1");
+            var n2 = helper.getNode("n2");
+            n2.on("input", function(msg) {
+                try {
+                    msg.should.have.property("payload");
+                    msg.payload.should.equal("A,B,C,D");
+                    done();
+                }
+                catch(e) {done(e);}
+            });
+            n1.receive({payload:"A", parts:{id:1, type:"string", ch:",", index:0, count:4}});
+            n1.receive({payload:"B", parts:{id:1, type:"string", ch:",", index:1, count:4}});
+            n1.receive({payload:"C", parts:{id:1, type:"string", ch:",", index:2, count:4}});
+            n1.receive({payload:"D", parts:{id:1, type:"string", ch:",", index:3, count:4}});
+        });
+    });
+
     it('should join things into an array after a count', function(done) {
         var flow = [{id:"n1", type:"join", wires:[["n2"]], count:3, joiner:",",mode:"custom"},
                     {id:"n2", type:"helper"}];