# Function question

**URL:** <https://discourse.nodered.org/t/function-question/36572>\
**Category:** General\
**Created:** [26 November 2020 16:30 UTC](https://discourse.nodered.org/t/function-question/36572 "2020-11-26T16:30:50Z")\
**Posts on this page:** 9\
**Page:** 1

<div class="post-metadata">

**Author:** ![corin.corvus](https://avatars.discourse-cdn.com/v4/letter/c/7feea3/32.png) [@corin.corvus](https://discourse.nodered.org/u/corin.corvus)\
**Post date:** [26 November 2020 16:30 UTC](https://discourse.nodered.org/t/function-question/36572/1 "2020-11-26T16:30:51Z")

</div>

Hi,

i try to add a function in my flow.

i have 2 inputs:  
playstate of my sonos speaker = **msg.payload.play**  
powerstate of my kenwood amp = **msg.payload.kenwood**

I want toggle my Amp, if the playstate and powerstate are not identical.  
The Flow change the inputs of the nodes to "true" and "false" for the dashboard switches.  
After i changed it in numbers 1,0 for the function.

For toggle my Amp i only have one trigger with a http request to an arduino IR Remote.

Second:  
if i pause or stop the Sonos Playstate, the amp should not switch immediately

May you help me?

## Thanks

* * *

My function is:

```auto
var m_out=[];
var play=msg.payload.play;
var kenwood=msg.payload.kenwood;

if (play !== kenwood){
    m_out = {payload:1}
} else null;

return msg;

```

 ![grafik](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/3/0/303e12a5b0b34e03303d722d2dd5a97e1043ec92.png)

Flow:

```auto
[{"id":"7c9b27df.0bc7d8","type":"tab","label":"Kenwood","disabled":false,"info":""},{"id":"5df92dda.dfb934","type":"http request","z":"7c9b27df.0bc7d8","name":"","method":"GET","ret":"txt","paytoqs":false,"url":"http://10.2.0.65/ir?code=501397830","tls":"","persist":false,"proxy":"","authType":"","x":1190,"y":300,"wires":[[]]},{"id":"367ccdfb.1ecbd2","type":"mqtt in","z":"7c9b27df.0bc7d8","name":"","topic":"shellies/shelly-wohnzimmer-kenwood/relay/0/power","qos":"0","datatype":"auto","broker":"8aa7c4c7.b6d308","x":250,"y":300,"wires":[["26017241.60409e"]]},{"id":"26017241.60409e","type":"switch","z":"7c9b27df.0bc7d8","name":">= 10 <= 10","property":"payload","propertyType":"msg","rules":[{"t":"gte","v":"10","vt":"str"},{"t":"lte","v":"10","vt":"str"}],"checkall":"true","repair":false,"outputs":2,"x":570,"y":300,"wires":[["60a41f75.b66858"],["fdf91316.f38878"]]},{"id":"60a41f75.b66858","type":"change","z":"7c9b27df.0bc7d8","name":"An","rules":[{"t":"delete","p":"payload","pt":"msg"},{"t":"set","p":"payload","pt":"msg","to":"true","tot":"bool"},{"t":"set","p":"topic","pt":"msg","to":"kenwood","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":750,"y":280,"wires":[["145376e3.77b791","dd123a68.ad29e"]]},{"id":"fdf91316.f38878","type":"change","z":"7c9b27df.0bc7d8","name":"Aus","rules":[{"t":"delete","p":"payload","pt":"msg"},{"t":"set","p":"payload","pt":"msg","to":"false","tot":"bool"},{"t":"set","p":"topic","pt":"msg","to":"kenwood","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":750,"y":320,"wires":[["145376e3.77b791","dd123a68.ad29e"]]},{"id":"f6ba6b85.8e56c","type":"comment","z":"7c9b27df.0bc7d8","name":"Schalter Kenwood Anlage","info":"","x":150,"y":40,"wires":[]},{"id":"ebbbb832.a8e74","type":"change","z":"7c9b27df.0bc7d8","name":"AN","rules":[{"t":"delete","p":"payload","pt":"msg"},{"t":"set","p":"payload","pt":"msg","to":"true","tot":"bool"}],"action":"","property":"","from":"","to":"","reg":false,"x":570,"y":100,"wires":[["5a81caf4.f5dbf4"]]},{"id":"7d3519c8.f761c8","type":"switch","z":"7c9b27df.0bc7d8","name":"","property":"payload","propertyType":"msg","rules":[{"t":"eq","v":"playing","vt":"str"},{"t":"eq","v":"paused","vt":"str"},{"t":"eq","v":"stopped","vt":"str"}],"checkall":"true","repair":false,"outputs":3,"x":370,"y":120,"wires":[["ebbbb832.a8e74"],["bbd4a08f.eda1a"],["bbd4a08f.eda1a"]]},{"id":"bbd4a08f.eda1a","type":"change","z":"7c9b27df.0bc7d8","name":"AUS","rules":[{"t":"delete","p":"payload","pt":"msg"},{"t":"set","p":"payload","pt":"msg","to":"false","tot":"bool"}],"action":"","property":"","from":"","to":"","reg":false,"x":570,"y":140,"wires":[["5a81caf4.f5dbf4"]]},{"id":"5a81caf4.f5dbf4","type":"ui_switch","z":"7c9b27df.0bc7d8","name":"","label":"Playstate","tooltip":"","group":"87b21765.57daa8","order":12,"width":0,"height":0,"passthru":true,"decouple":"false","topic":"","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":740,"y":120,"wires":[["319eb34a.a9f5dc"]]},{"id":"adce622b.eefea","type":"link in","z":"7c9b27df.0bc7d8","name":"Sonos Playstate Wohnzimmer","links":["8026b813.baa0b"],"x":235,"y":120,"wires":[["7d3519c8.f761c8"]]},{"id":"d5746361.9c5248","type":"debug","z":"7c9b27df.0bc7d8","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":1650,"y":180,"wires":[]},{"id":"145376e3.77b791","type":"ui_switch","z":"7c9b27df.0bc7d8","name":"","label":"Kenwood Anlage","tooltip":"","group":"87b21765.57daa8","order":11,"width":0,"height":0,"passthru":false,"decouple":"true","topic":"","style":"","onvalue":"true","onvalueType":"bool","onicon":"","oncolor":"","offvalue":"false","offvalueType":"bool","officon":"","offcolor":"","x":950,"y":300,"wires":[["5df92dda.dfb934"]]},{"id":"319eb34a.a9f5dc","type":"change","z":"7c9b27df.0bc7d8","name":"","rules":[{"t":"move","p":"payload","pt":"msg","to":"payload.play","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":960,"y":120,"wires":[["186cecfe.5ba32b"]]},{"id":"dd123a68.ad29e","type":"change","z":"7c9b27df.0bc7d8","name":"","rules":[{"t":"move","p":"payload","pt":"msg","to":"payload.kenwood","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":960,"y":240,"wires":[["186cecfe.5ba32b"]]},{"id":"186cecfe.5ba32b","type":"change","z":"7c9b27df.0bc7d8","name":"","rules":[{"t":"set","p":"topic","pt":"msg","to":"switch","tot":"str"},{"t":"change","p":"payload.play","pt":"msg","from":"true","fromt":"bool","to":"1","tot":"num"},{"t":"change","p":"payload.play","pt":"msg","from":"false","fromt":"bool","to":"0","tot":"num"},{"t":"change","p":"payload.kenwood","pt":"msg","from":"true","fromt":"bool","to":"1","tot":"num"},{"t":"change","p":"payload.kenwood","pt":"msg","from":"false","fromt":"bool","to":"0","tot":"num"}],"action":"","property":"","from":"","to":"","reg":false,"x":1220,"y":180,"wires":[["78496e03.fe4d18"]]},{"id":"78496e03.fe4d18","type":"function","z":"7c9b27df.0bc7d8","name":"","func":"var m_out=[];\nvar play=msg.payload.play;\nvar kenwood=msg.payload.kenwood;\n\nif (play !== kenwood){\n m_out = {payload:1}\n} else null;\n\nreturn msg;","outputs":1,"noerr":0,"x":1430,"y":180,"wires":[["d5746361.9c5248"]]},{"id":"8aa7c4c7.b6d308","type":"mqtt-broker","z":"","name":"Mosquitto","broker":"10.0.0.171","port":"1883","clientid":"","usetls":false,"compatmode":false,"keepalive":"60","cleansession":true,"birthTopic":"","birthQos":"0","birthPayload":"","closeTopic":"","closeQos":"0","closePayload":"","willTopic":"","willQos":"0","willPayload":""},{"id":"87b21765.57daa8","type":"ui_group","z":"","name":"Main","tab":"7c6fa6e7.e5b808","order":1,"disp":true,"width":8,"collapse":false},{"id":"7c6fa6e7.e5b808","type":"ui_tab","z":"","name":"Home","icon":"dashboard","order":1,"disabled":false,"hidden":false}]

```

---

<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:** [26 November 2020 16:36 UTC](https://discourse.nodered.org/t/function-question/36572/2 "2020-11-26T16:36:15Z")

</div>

Messages never arrive at the same time so you need to either store the values or use a join node.

See [this article in the cookbook](https://cookbook.nodered.org/basic/join-streams) for an example of how to join messages into one object.

---

<div class="post-metadata">

**Author:** ![corin.corvus](https://avatars.discourse-cdn.com/v4/letter/c/7feea3/32.png) [@corin.corvus](https://discourse.nodered.org/u/corin.corvus)\
**Post date:** [26 November 2020 17:01 UTC](https://discourse.nodered.org/t/function-question/36572/3 "2020-11-26T17:01:10Z")

</div>

Thank you.

now the Inputs come at the same time.

I stuck in the function:  
var play=msg.payload.play;  
var kenwood=msg.payload.kenwood;

if (play !== kenwood){  
???????  
} else null;

return msg;

---

<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:** [26 November 2020 17:05 UTC](https://discourse.nodered.org/t/function-question/36572/4 "2020-11-26T17:05:49Z")

</div>

> [@corin.corvus](#):
>
> I stuck in the function:

yeah - ok - so what are you trying to do?

if you want to halt the flow of a `msg`, you can return null...

```auto
var play=msg.payload.play;
var kenwood=msg.payload.kenwood;

if (play !== kenwood){
  //what do you want to happen here?
  msg.payload = 1; //e.g. set msg.payload?
} else {
  //return null to stop the msg travelling to next node
  return null;
}

return msg; //send msg to next node by returning the msg.

```

---

<div class="post-metadata">

**Author:** ![corin.corvus](https://avatars.discourse-cdn.com/v4/letter/c/7feea3/32.png) [@corin.corvus](https://discourse.nodered.org/u/corin.corvus)\
**Post date:** [26 November 2020 17:27 UTC](https://discourse.nodered.org/t/function-question/36572/5 "2020-11-26T17:27:05Z")

</div>

play can be: true/false  
kenwood can be true/false  
(i can change it in numbers if easier)

if play and kenwood are both true, do nothing  
if play and kenwood are both false, do nothing  
if play true and kenwood false, trigger next steps  
if play false and kenwood true, trigger next steps

next step is a single node with http request to toggle the kenwood amp power (on and off)  
the variable "kenwood" is a shelly plug s with power Measurement over mqtt. unter 10 watt is off/false, over 10 watt is on/true

---

<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:** [26 November 2020 17:33 UTC](https://discourse.nodered.org/t/function-question/36572/6 "2020-11-26T17:33:43Z")

</div>

```javascript
var play=msg.payload.play;
var kenwood=msg.payload.kenwood;

// if play and kenwood are both true, do nothing
if (play == true && kenwood == true) return null; //do nothing

// if play and kenwood are both false, do nothing
if (play == false && kenwood == false) return null; //do nothing

// if play true and kenwood false, trigger next steps
// if play false and kenwood true, trigger next steps
return msg; //send msg to next node by returning the msg.

```

---

<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:** [26 November 2020 17:51 UTC](https://discourse.nodered.org/t/function-question/36572/7 "2020-11-26T17:51:31Z")

</div>

Or

```auto
if (play == kenwood) msg = null
return msg

```

---

<div class="post-metadata">

**Author:** ![corin.corvus](https://avatars.discourse-cdn.com/v4/letter/c/7feea3/32.png) [@corin.corvus](https://discourse.nodered.org/u/corin.corvus)\
**Post date:** [26 November 2020 17:55 UTC](https://discourse.nodered.org/t/function-question/36572/8 "2020-11-26T17:55:50Z")

</div>

It works now!  
Thank you @Steve-Mcl and @Colin for the second option 🙂

---

<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 December 2020 17:55 UTC](https://discourse.nodered.org/t/function-question/36572/9 "2020-12-10T17:55:55Z")

</div>

Closed on 10 December 2020 17:55 UTC

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