# Clarifying use of split node

**URL:** <https://discourse.nodered.org/t/clarifying-use-of-split-node/43091>\
**Category:** General\
**Created:** [23 March 2021 17:21 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091 "2021-03-23T17:21:10Z")\
**Posts on this page:** 18\
**Page:** 1

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**Author:** ![fmarzocca](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/fmarzocca/32/35901_2.png) [@fmarzocca](https://discourse.nodered.org/u/fmarzocca)\
**Post date:** [23 March 2021 17:21 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/1 "2021-03-23T17:21:11Z")

</div>

Hi, I need a clarification on use of split node.  
I have an incoming message like this one:  
`*#*1##*#*1##*5*1*##*5*5*##*5*7*##*5*9*##*5*18*#1##*5*18*#2##*5*18*#3##*5*18*#4##*5*11*#5##*5*11*#6##*5*11*#7##*5*11*#8##`

and I need to split it into several frames using "##" as a separator. I thought to use a split node splitting on "##", then (at output) add again the "##" to fill the frames back:

`msg.payload = msg.payload.concat("##");`

In such a way I should have a sequence of frames, from the original single message. Is it correct? Do I need a `join` node (and why?)

 ![Schermata 2021-03-23 alle 18.21.41](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/0/2/02b5b5bc2c5d017b20a12edf5e61b681bac0a589.png)

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [23 March 2021 17:40 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/2 "2021-03-23T17:40:17Z")

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What comes out of the split node and what comes out of the function node adding it back?

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [23 March 2021 17:50 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/3 "2021-03-23T17:50:21Z")

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It works ok for me

```auto
[{"id":"8ccd7975.e2417","type":"inject","z":"84405ff5.25fa6","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"*#*1##*#*1##*5*1*##*5*5*##*5*7*##*5*9*##*5*18*#1##*5*18*#2##*5*18*#3##*5*18*#4##*5*11*#5##*5*11*#6##*5*11*#7##*5*11*#8##","payloadType":"str","x":100,"y":1480,"wires":[["febf1037.257068"]]},{"id":"febf1037.257068","type":"split","z":"84405ff5.25fa6","name":"","splt":"##","spltType":"str","arraySplt":1,"arraySpltType":"len","stream":false,"addname":"","x":230,"y":1480,"wires":[["940431f2.fa6de"]]},{"id":"940431f2.fa6de","type":"function","z":"84405ff5.25fa6","name":"","func":"msg.payload = msg.payload.concat(\"##\");\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":360,"y":1480,"wires":[["4c5b48fb.c32b1"]]},{"id":"4c5b48fb.c32b1","type":"debug","z":"84405ff5.25fa6","name":"true","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":430,"y":1540,"wires":[]}]

```

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<div class="post-metadata">

**Author:** ![fmarzocca](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/fmarzocca/32/35901_2.png) [@fmarzocca](https://discourse.nodered.org/u/fmarzocca)\
**Post date:** [23 March 2021 17:56 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/4 "2021-03-23T17:56:44Z")

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Yes, it works. Sorry, my question was not complete. I meant: is this the correct (and most efficient) way to do this?

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<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [23 March 2021 18:26 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/5 "2021-03-23T18:26:57Z")

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> [@fmarzocca](#):
>
> is this the correct (and most efficient) way to do this?

  

> Correct?

That is subjective. It is probably a more "node-red" way of doing it.

  

* * *

> Most efficient way?

no.  
It is about 4 times slower than a straight function...

![XHR9COuAl6](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/7/1/71fa78795c2bf8313852a6383ac2e294f88df772.gif)  
... the top flow is using split node - averages around 22ms  
the botttom flow is using a function to get the same results - averages around 6ms

Function code...

```auto
msg.payload.split("##").forEach(e => { node.send({ payload: e + "##"}) });

```

  

* * *

I have asked before but never got an answer, what generates that long data string?  
If you do, then I would personally suggest you stop working with all this string concatenation and splitting. Using strings like this is possibly one of the least efficient way of working.

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [23 March 2021 18:31 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/6 "2021-03-23T18:31:27Z")

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Since you are already using a function node you might as well do it all in the one function node.

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<div class="post-metadata">

**Author:** ![fmarzocca](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/fmarzocca/32/35901_2.png) [@fmarzocca](https://discourse.nodered.org/u/fmarzocca)\
**Post date:** [23 March 2021 18:32 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/7 "2021-03-23T18:32:04Z")

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I cannot avoid them. They are generated by a closed proprietary home automation server (Legrand) and I have no access to edit its frames.  
Thank you!

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<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [23 March 2021 18:34 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/8 "2021-03-23T18:34:28Z")

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(speculation) In which case, depending on how much processing and passing you do, it might be wise to generate objects at the start of your flows and pass those around.

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<div class="post-metadata">

**Author:** ![fmarzocca](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/fmarzocca/32/35901_2.png) [@fmarzocca](https://discourse.nodered.org/u/fmarzocca)\
**Post date:** [23 March 2021 18:35 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/9 "2021-03-23T18:35:52Z")

</div>

that's not easy... Messages can be like the one I am reporting at the first post, or just singles frames. Messages length is not fixed. The only standard thing is that each frame is closed by "##"...

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<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [23 March 2021 18:37 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/10 "2021-03-23T18:37:53Z")

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Sure it's easy. Explain to me a few of those frames and I'll show you. (I'll need a bit context too, like what you use the parts for)

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<div class="post-metadata">

**Author:** ![fmarzocca](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/fmarzocca/32/35901_2.png) [@fmarzocca](https://discourse.nodered.org/u/fmarzocca)\
**Post date:** [23 March 2021 18:42 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/11 "2021-03-23T18:42:33Z")

</div>

Each frame has its own meaning (automation/lights/alarm/contacts/etc).  
This is just a short excerpt from the log:

```auto
2021-03-23 16:51:32,288 - *#13**#1*02*23*03*2021##
2021-03-23 16:51:33,099 - *#13**#0*16*50*00*001##
2021-03-23 16:51:58,163 - *#1*0113*6*0##
2021-03-23 16:53:33,812 - *#4*200*15*1*0128*0001##
2021-03-23 16:56:57,655 - *#1*0113*6*0##
2021-03-23 16:58:22,615 - *#4*800*15*1*0215*0001##
2021-03-23 17:01:32,378 - *#13**#1*02*23*03*2021##
2021-03-23 17:01:33,176 - *#13**#0*17*00*00*001##
2021-03-23 17:01:57,156 - *#1*0113*6*0##
2021-03-23 17:06:56,594 - *#1*0113*6*0##
2021-03-23 17:09:05,607 - *25*32#1*385##
2021-03-23 17:11:09,525 - *#4*200*15*1*0125*0001##
2021-03-23 17:11:32,903 - *#13**#1*02*23*03*2021##
2021-03-23 17:11:33,972 - *#13**#0*17*10*00*001##
2021-03-23 17:11:56,042 - *#1*0113*6*0##
2021-03-23 17:13:30,610 - *1*34*0113##
2021-03-23 17:13:34,661 - *1*34*0113##
2021-03-23 17:13:37,142 - *25*31#1*311##

```

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<div class="post-metadata">

**Author:** ![fmarzocca](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/fmarzocca/32/35901_2.png) [@fmarzocca](https://discourse.nodered.org/u/fmarzocca)\
**Post date:** [23 March 2021 20:37 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/13 "2021-03-23T20:37:54Z")

</div>

Thank you Steve for your kind support!

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<div class="post-metadata">

**Author:** ![fmarzocca](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/fmarzocca/32/35901_2.png) [@fmarzocca](https://discourse.nodered.org/u/fmarzocca)\
**Post date:** [27 March 2021 09:28 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/14 "2021-03-27T09:28:29Z")

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@Steve-Mcl , what did you use to measure flow performances? I may be interested in other measures.

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<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [27 March 2021 10:48 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/15 "2021-03-27T10:48:14Z")

</div>

It is a simple subflow i knocked up for times like this 😛

You can grab it from here...

[https://flows.nodered.org/flow/63f29373e826a9fd4943d679d43e725f](https://flows.nodered.org/flow/63f29373e826a9fd4943d679d43e725f)

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<div class="post-metadata">

**Author:** ![fmarzocca](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/fmarzocca/32/35901_2.png) [@fmarzocca](https://discourse.nodered.org/u/fmarzocca)\
**Post date:** [27 March 2021 11:29 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/16 "2021-03-27T11:29:59Z")

</div>

Cool!

From my tests it seems that substr() or IndexOf() is faster than match(regex). Do you agree?

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<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [27 March 2021 12:11 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/17 "2021-03-27T12:11:57Z")

</div>

> [@fmarzocca](#):
>
> it seems that substr() or IndexOf() is faster than match(regex). Do you agree?

That would make sense. regex is (can be) a complex beast. substr and indexOf are simple array slicing (as in an array of chars not a JS array)

however, as i have said before, working with strings in throughout your flow not ideal. You really should parse your strings (at the first opportunity) into usable/sensible objects with string/number/bool props (as appropriate) (for of a few reasons I'll not go into again)

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<div class="post-metadata">

**Author:** ![fmarzocca](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/fmarzocca/32/35901_2.png) [@fmarzocca](https://discourse.nodered.org/u/fmarzocca)\
**Post date:** [27 March 2021 12:42 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/18 "2021-03-27T12:42:54Z")

</div>

Yes, I'm following your advise, that's why I am testing regex and string slicing in order to transform the initial string frame into an object. Regex is much easier for this, while string slicing involve much more attention and can possibly introduce errors.

As an example, I am transforming the frame (string) `"*25*32#1*341##"` into this:

![Schermata 2021-03-27 alle 13.42.35](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/5/5/55034defcdfbdce19e01c4b5b3e3bb7a87700f47.png)

With regex, it is a simple matter of this function:

```auto
var r=/^\*(\d+)\*(\d+)#(\d)\*3(\d+)##/g
if (!msg.payload.match(r)) return;
var m= msg.payload.split(r);
msg.payload = {who: m[1], what: m[2], param: m[3], where:m[4]};
return msg;

```

While with indexOf() or substr() it is much more complex.

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [10 April 2021 12:43 UTC](https://discourse.nodered.org/t/clarifying-use-of-split-node/43091/19 "2021-04-10T12:43:31Z")

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