# Return data from context.get

**URL:** <https://discourse.nodered.org/t/return-data-from-context-get/70544>\
**Category:** General\
**Tags:** home-assistant\
**Created:** [13 November 2022 17:58 UTC](https://discourse.nodered.org/t/return-data-from-context-get/70544 "2022-11-13T17:58:14Z")\
**Posts on this page:** 10\
**Page:** 1

<div class="post-metadata">

**Author:** ![vrabi-cv](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/vrabi-cv/32/70654_2.png) [@vrabi-cv](https://discourse.nodered.org/u/vrabi-cv)\
**Post date:** [13 November 2022 17:58 UTC](https://discourse.nodered.org/t/return-data-from-context-get/70544/1 "2022-11-13T17:58:14Z")

</div>

Hello, I am newbie into the homeassistant as well as programming, but I have made some simple thing in my home automation and now I want to check if temperature sensor is not "Stucked" at same value. I try to use counting average of values inside array. But I keep failing to get the sum of values which results in reading the value as "NaN"  
the code is here

```auto
[{"id":"ec5e2d42a7a7d10c","type":"group","z":"9612339af2b7a062","style":{"stroke":"#999999","stroke-opacity":"1","fill":"none","fill-opacity":"1","label":true,"label-position":"nw","color":"#a4a4a4"},"nodes":["d6c798ea44439013","3f9a57148997b2b5","4b9957a836089d27","9ceed4fa7b44f754","221b4840bbaa2af2","8a96f49405a2d131","70468ddeb3e03c94","14a4389d84d19d5d","d3342f56cda85414","2207a872a0db52f2","a767b2af1fd07b22","02f3b4631ed8305f"],"x":-6,"y":819,"w":1092,"h":488},{"id":"d6c798ea44439013","type":"api-call-service","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","name":"notifikace na mobil","server":"35bd0ff1.ef0de","version":5,"debugenabled":false,"domain":"notify","service":"mobile_app_p30_pro_martin","areaId":[],"deviceId":[],"entityId":[],"data":"{\"message\":\"{{payload}} má asi nefunkční měření v čase {{cas}}\",\"title\":\"{{title}}\"}","dataType":"json","mergeContext":"","mustacheAltTags":false,"outputProperties":[],"queue":"all","x":890,"y":1000,"wires":[[]]},{"id":"3f9a57148997b2b5","type":"moment","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","name":"","topic":"","input":"cas","inputType":"msg","inTz":"Europe/Prague","adjAmount":"0","adjType":"hours","adjDir":"add","format":"HH:mm:ss","locale":"C","output":"cas","outputType":"msg","outTz":"Europe/Prague","x":960,"y":940,"wires":[["d6c798ea44439013"]]},{"id":"4b9957a836089d27","type":"comment","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","name":"Kontrola funkčnosti čidla teploty","info":"","x":150,"y":860,"wires":[]},{"id":"9ceed4fa7b44f754","type":"inject","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","name":"12 min","props":[{"p":"cas","v":"","vt":"date"},{"p":"title","v":"Nefunkční teploměr","vt":"str"}],"repeat":"720","crontab":"","once":false,"onceDelay":0.1,"topic":"","x":120,"y":940,"wires":[["221b4840bbaa2af2"]]},{"id":"221b4840bbaa2af2","type":"change","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","name":"teplota bojler?","rules":[{"t":"set","p":"bojler","pt":"msg","to":"tep_bojler","tot":"global"},{"t":"set","p":"pocitadlo","pt":"msg","to":"1","tot":"str"},{"t":"set","p":"payload","pt":"msg","to":"Bojler","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":300,"y":940,"wires":[["d3342f56cda85414"]]},{"id":"8a96f49405a2d131","type":"link out","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","name":"link out 3","mode":"link","links":["4230cb89beb71088","be25093ffe136f54"],"x":755,"y":940,"wires":[]},{"id":"70468ddeb3e03c94","type":"link in","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","name":"link in 3","links":["56bbb26dcbfb594d"],"x":815,"y":940,"wires":[["3f9a57148997b2b5"]]},{"id":"14a4389d84d19d5d","type":"inject","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","name":"reset počítadla o půlnoci","props":[{"p":"topic","vt":"str"}],"repeat":"","crontab":"00 00 * * *","once":false,"onceDelay":0.1,"topic":"reset","x":170,"y":1000,"wires":[["221b4840bbaa2af2"]]},{"id":"d3342f56cda85414","type":"function","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","name":"function 3","func":"var myArray = context.get(\"myArray\");\nvar maxdelka = 5;\nvar soucet = context.get(\"sum\") || 1;\nvar i = context.get(\"i\") || 1 ;\n\nif (!myArray) {\n console.log(\"Set the array on context memory\");\n context.set(\"myArray\", []);\n myArray = context.get(\"myArray\");\n \n}\n\nmyArray.push(msg.bojler);\n\nif ( i <= maxdelka ) { \n i++;\n soucet += myArray[i];\n \n} \nelse {\n i++ ;\n myArray.splice(0 , 1);\n soucet += myArray[i];\n}\n\nmsg.prumer = soucet / myArray.length;\ncontext.set(\"sum\", soucet);\nmsg.soucet = soucet;\n\nmsg.delka = myArray.length;\nmsg.bojler = myArray;\n\ncontext.set(\"i\", i);\nmsg.i = i;\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":460,"y":940,"wires":[["a767b2af1fd07b22","2207a872a0db52f2"]]},{"id":"2207a872a0db52f2","type":"debug","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","name":"debug 34","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":660,"y":1020,"wires":[]},{"id":"a767b2af1fd07b22","type":"switch","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","name":"bojler <> průměr","property":"prumer","propertyType":"msg","rules":[{"t":"eq","v":"tep_bojler","vt":"global"}],"checkall":"true","repair":false,"outputs":1,"x":640,"y":940,"wires":[["8a96f49405a2d131"]]},{"id":"02f3b4631ed8305f","type":"group","z":"9612339af2b7a062","g":"ec5e2d42a7a7d10c","style":{"stroke":"#999999","stroke-opacity":"1","fill":"none","fill-opacity":"1","label":true,"label-position":"nw","color":"#a4a4a4"},"nodes":["b73222750ed45624","951f1ae8562c96c2","678faf3c98fdeacc","4230cb89beb71088","56bbb26dcbfb594d","e6c8689b81fa0af3"],"x":314,"y":1079,"w":492,"h":202},{"id":"b73222750ed45624","type":"switch","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"počet >5","property":"pocitadlo","propertyType":"msg","rules":[{"t":"gt","v":"5","vt":"num"}],"checkall":"true","repair":false,"outputs":1,"x":640,"y":1180,"wires":[["678faf3c98fdeacc","56bbb26dcbfb594d"]]},{"id":"951f1ae8562c96c2","type":"function","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"Counter","func":"// Define Variable and get stored flow value\n// if there is no stored value, then the value is 0\nvar counter = flow.get(\"counter\") || 0\n\n// Check the msg.topic property\n// If the topic is equal to reset then set the counter to 0\n// else add 1 to the counter value\nif (msg.topic == \"reset\") {\n counter = 1\n} else {\n counter ++\n}\n\n// save the counter value in the flow variable\nflow.set(\"counter\", counter)\n\n// set msg.payload to counter value\nmsg.pocitadlo = counter\n\n// return msg Object\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":480,"y":1180,"wires":[["b73222750ed45624"]]},{"id":"678faf3c98fdeacc","type":"change","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"reset","rules":[{"t":"set","p":"topic","pt":"msg","to":"reset","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":550,"y":1240,"wires":[["951f1ae8562c96c2"]]},{"id":"4230cb89beb71088","type":"link in","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"link in 2","links":["8a96f49405a2d131"],"x":355,"y":1180,"wires":[["951f1ae8562c96c2"]]},{"id":"56bbb26dcbfb594d","type":"link out","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"link out 2","mode":"link","links":["70468ddeb3e03c94"],"x":765,"y":1180,"wires":[]},{"id":"e6c8689b81fa0af3","type":"comment","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"počítadlo do 5ti","info":"","x":540,"y":1120,"wires":[]},{"id":"35bd0ff1.ef0de","type":"server","name":"Home Assistant","version":5,"addon":true,"rejectUnauthorizedCerts":true,"ha_boolean":"y|yes|true|on|home|open","connectionDelay":true,"cacheJson":true,"heartbeat":false,"heartbeatInterval":30,"areaSelector":"friendlyName","deviceSelector":"friendlyName","entitySelector":"friendlyName","statusSeparator":"at: ","statusYear":"hidden","statusMonth":"short","statusDay":"numeric","statusHourCycle":"h23","statusTimeFormat":"h:m","enableGlobalContextStore":true}]

```

---

<div class="post-metadata">

**Author:** ![zenofmud](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zenofmud/32/316_2.png) [@zenofmud](https://discourse.nodered.org/u/zenofmud)\
**Post date:** [13 November 2022 18:40 UTC](https://discourse.nodered.org/t/return-data-from-context-get/70544/2 "2022-11-13T18:40:53Z")

</div>

@vrabi-cv welcome to the forum!

It looks like you are talking about the `function` node labeled 'function 3'.  
First line of that function is  
`var myArray = context.get("myArray");`  
why not use  
`var myArray = context.get("myArray") || [];`  
to initilize it?

Add a `debug` node (set to display the complete msg object) to the output of the `change` node 'teplota bojler?' so you can see what it is sending in.

Change the `console.log` to `node.warn` and you will see it in the debug sidebar - makes it easier to debug.

Add `node.warn('something = ' + something)` to display the value of variables you are using - Node, you need to change `something` to the name of your variable you want to see.

I would also an `inject` node, with msg.payload set to `"clear" and then in the function node add the following at the very beginning:

```auto
if (msg.payload == "clear") {
    context.set('i')
    context.set('myArray')
    context.set('sum')
    return
}

```

this will give you an easy way to clear out the context variables for testing.

Doing this you should be able to see what your code `is doing` and then you can figure out how to get it to do `what you want it to do`. 😁

---

<div class="post-metadata">

**Author:** ![vrabi-cv](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/vrabi-cv/32/70654_2.png) [@vrabi-cv](https://discourse.nodered.org/u/vrabi-cv)\
**Post date:** [13 November 2022 20:52 UTC](https://discourse.nodered.org/t/return-data-from-context-get/70544/3 "2022-11-13T20:52:08Z")

</div>

Thank you for your response. You are right my issue is inside the function 3.  
The initialization of array does not work for me, so I use my code for it. Anyway I used the "clearing" and "node.warn" for debugging and the problem is "soucet += myArray[i];" this code results in NaN. If I debug "myArray[i];" while i=1, I receive NaN. If I debug "myArray[1];" I receive 23,1. Could there be some problem in the "i" variable setting?  
THX Martin.

---

<div class="post-metadata">

**Author:** ![zenofmud](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zenofmud/32/316_2.png) [@zenofmud](https://discourse.nodered.org/u/zenofmud)\
**Post date:** [13 November 2022 21:04 UTC](https://discourse.nodered.org/t/return-data-from-context-get/70544/4 "2022-11-13T21:04:07Z")

</div>

I don't know if this will help you solve the problem but remember the first element of an array is index 0. So if you have an array  
`cars = ["Saab", "Volvo", "BMW"];`  
the first element "Saab" is addressed as `cars[0]`

---

<div class="post-metadata">

**Author:** ![vrabi-cv](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/vrabi-cv/32/70654_2.png) [@vrabi-cv](https://discourse.nodered.org/u/vrabi-cv)\
**Post date:** [13 November 2022 21:22 UTC](https://discourse.nodered.org/t/return-data-from-context-get/70544/5 "2022-11-13T21:22:10Z")

</div>

I am aware of this.  
I did not write the result correctly in my previous post...these are correct results:  
If I debug "myArray[i];" while i=0, I receive Undefined.  
If I debug "myArray[0];" I receive 35,94 (current value of the temp).

Picture of debug after 1st run of code:  
 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/7/2/721c0516c6e2a38b3345bae5903df88da99c98f1.png)

Picture of debug after 2nd run of code:  
 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/5/0/505f44d088e961a626c077abe8747fb4c4d29970.png)

I am lost why this simple thing does not work.

---

<div class="post-metadata">

**Author:** ![zenofmud](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zenofmud/32/316_2.png) [@zenofmud](https://discourse.nodered.org/u/zenofmud)\
**Post date:** [13 November 2022 22:08 UTC](https://discourse.nodered.org/t/return-data-from-context-get/70544/6 "2022-11-13T22:08:05Z")

</div>

Export your current flow and I’ll take a look

---

<div class="post-metadata">

**Author:** ![vrabi-cv](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/vrabi-cv/32/70654_2.png) [@vrabi-cv](https://discourse.nodered.org/u/vrabi-cv)\
**Post date:** [13 November 2022 22:20 UTC](https://discourse.nodered.org/t/return-data-from-context-get/70544/7 "2022-11-13T22:20:11Z")

</div>

here is the flow:

```auto
[{"id":"d6c798ea44439013","type":"api-call-service","z":"9612339af2b7a062","name":"notifikace na mobil","server":"35bd0ff1.ef0de","version":5,"debugenabled":false,"domain":"notify","service":"mobile_app_p30_pro_martin","areaId":[],"deviceId":[],"entityId":[],"data":"{\"message\":\"Bojler má asi nefunkční měření v čase {{cas}}\",\"title\":\"{{title}}\"}","dataType":"json","mergeContext":"","mustacheAltTags":false,"outputProperties":[],"queue":"all","x":890,"y":1000,"wires":[[]]},{"id":"3f9a57148997b2b5","type":"moment","z":"9612339af2b7a062","name":"","topic":"","input":"cas","inputType":"msg","inTz":"Europe/Prague","adjAmount":"0","adjType":"hours","adjDir":"add","format":"HH:mm:ss","locale":"C","output":"cas","outputType":"msg","outTz":"Europe/Prague","x":960,"y":940,"wires":[["d6c798ea44439013"]]},{"id":"4b9957a836089d27","type":"comment","z":"9612339af2b7a062","name":"Kontrola funkčnosti čidla teploty","info":"","x":150,"y":860,"wires":[]},{"id":"9ceed4fa7b44f754","type":"inject","z":"9612339af2b7a062","name":"12 min","props":[{"p":"cas","v":"","vt":"date"},{"p":"title","v":"Nefunkční teploměr","vt":"str"}],"repeat":"720","crontab":"","once":false,"onceDelay":0.1,"topic":"","x":120,"y":940,"wires":[["221b4840bbaa2af2"]]},{"id":"221b4840bbaa2af2","type":"change","z":"9612339af2b7a062","name":"teplota bojler?","rules":[{"t":"set","p":"bojler","pt":"msg","to":"tep_bojler","tot":"global"},{"t":"set","p":"pocitadlo","pt":"msg","to":"1","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":300,"y":940,"wires":[["d3342f56cda85414"]]},{"id":"8a96f49405a2d131","type":"link out","z":"9612339af2b7a062","name":"link out 3","mode":"link","links":["4230cb89beb71088","be25093ffe136f54"],"x":755,"y":940,"wires":[]},{"id":"70468ddeb3e03c94","type":"link in","z":"9612339af2b7a062","name":"link in 3","links":["56bbb26dcbfb594d"],"x":815,"y":940,"wires":[["3f9a57148997b2b5"]]},{"id":"14a4389d84d19d5d","type":"inject","z":"9612339af2b7a062","name":"reset počítadla o půlnoci","props":[{"p":"topic","vt":"str"},{"p":"payload"}],"repeat":"","crontab":"00 00 * * *","once":false,"onceDelay":0.1,"topic":"reset","payload":"clear","payloadType":"str","x":170,"y":1000,"wires":[["221b4840bbaa2af2"]]},{"id":"d3342f56cda85414","type":"function","z":"9612339af2b7a062","name":"function 3","func":"var myArray = context.get(\"myArray\");\nvar maxdelka = 5;\nvar soucet = context.get(\"sum\") || 0;\nvar i = context.get(\"i\") || 0;\n\nif (msg.payload == \"clear\") {\n context.set(\"i\");\n context.set(\"myArray\");\n context.set(\"sum\");\n return;\n}\n\nif (!myArray) {\n node.warn(\"Set the array on context memory\");\n context.set(\"myArray\", []);\n myArray = context.get(\"myArray\");\n \n}\n\nmyArray.push(msg.bojler);\nnode.warn('i='+ i );\nnode.warn(\"myArray=\" + myArray);\n\nif ( i <= maxdelka ) { \n i++;\n soucet += myArray[i];\n node.warn('myArray[i]=' + myArray[i]);\n node.warn('myArray[0]=' + myArray[0]);\n node.warn('myArray[1]=' + myArray[1]);\n node.warn('myArray[2]=' + myArray[2]);\n node.warn('soucet=' + soucet);\n} \nelse {\n i++ ;\n myArray.splice(0 , 1);\n soucet += myArray[i];\n node.warn('soucet1=' + soucet);\n}\n\nmsg.prumer = soucet / myArray.length;\ncontext.set(\"sum\", soucet);\nmsg.soucet = soucet;\nnode.warn('soucet2=' + soucet);\n\nmsg.delka = myArray.length;\nmsg.bojler = myArray;\n\ncontext.set(\"i\", i);\nmsg.i = i;\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":460,"y":940,"wires":[["a767b2af1fd07b22","2207a872a0db52f2"]]},{"id":"2207a872a0db52f2","type":"debug","z":"9612339af2b7a062","name":"debug 34","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":660,"y":1020,"wires":[]},{"id":"a767b2af1fd07b22","type":"switch","z":"9612339af2b7a062","name":"bojler <> průměr","property":"prumer","propertyType":"msg","rules":[{"t":"eq","v":"tep_bojler","vt":"global"}],"checkall":"true","repair":false,"outputs":1,"x":640,"y":940,"wires":[["8a96f49405a2d131"]]},{"id":"02f3b4631ed8305f","type":"group","z":"9612339af2b7a062","style":{"stroke":"#999999","stroke-opacity":"1","fill":"none","fill-opacity":"1","label":true,"label-position":"nw","color":"#a4a4a4"},"nodes":["b73222750ed45624","951f1ae8562c96c2","678faf3c98fdeacc","4230cb89beb71088","56bbb26dcbfb594d","e6c8689b81fa0af3"],"x":314,"y":1079,"w":492,"h":202},{"id":"b73222750ed45624","type":"switch","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"počet >5","property":"pocitadlo","propertyType":"msg","rules":[{"t":"gt","v":"5","vt":"num"}],"checkall":"true","repair":false,"outputs":1,"x":640,"y":1180,"wires":[["678faf3c98fdeacc","56bbb26dcbfb594d"]]},{"id":"951f1ae8562c96c2","type":"function","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"Counter","func":"// Define Variable and get stored flow value\n// if there is no stored value, then the value is 0\nvar counter = flow.get(\"counter\") || 0\n\n// Check the msg.topic property\n// If the topic is equal to reset then set the counter to 0\n// else add 1 to the counter value\nif (msg.topic == \"reset\") {\n counter = 1\n} else {\n counter ++\n}\n\n// save the counter value in the flow variable\nflow.set(\"counter\", counter)\n\n// set msg.payload to counter value\nmsg.pocitadlo = counter\n\n// return msg Object\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":480,"y":1180,"wires":[["b73222750ed45624"]]},{"id":"678faf3c98fdeacc","type":"change","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"reset","rules":[{"t":"set","p":"topic","pt":"msg","to":"reset","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":550,"y":1240,"wires":[["951f1ae8562c96c2"]]},{"id":"4230cb89beb71088","type":"link in","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"link in 2","links":["8a96f49405a2d131"],"x":355,"y":1180,"wires":[["951f1ae8562c96c2"]]},{"id":"56bbb26dcbfb594d","type":"link out","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"link out 2","mode":"link","links":["70468ddeb3e03c94"],"x":765,"y":1180,"wires":[]},{"id":"e6c8689b81fa0af3","type":"comment","z":"9612339af2b7a062","g":"02f3b4631ed8305f","name":"počítadlo do 5ti","info":"","x":540,"y":1120,"wires":[]},{"id":"35bd0ff1.ef0de","type":"server","name":"Home Assistant","version":5,"addon":true,"rejectUnauthorizedCerts":true,"ha_boolean":"y|yes|true|on|home|open","connectionDelay":true,"cacheJson":true,"heartbeat":false,"heartbeatInterval":30,"areaSelector":"friendlyName","deviceSelector":"friendlyName","entitySelector":"friendlyName","statusSeparator":"at: ","statusYear":"hidden","statusMonth":"short","statusDay":"numeric","statusHourCycle":"h23","statusTimeFormat":"h:m","enableGlobalContextStore":true}]

```

---

<div class="post-metadata">

**Author:** ![zenofmud](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zenofmud/32/316_2.png) [@zenofmud](https://discourse.nodered.org/u/zenofmud)\
**Post date:** [13 November 2022 23:44 UTC](https://discourse.nodered.org/t/return-data-from-context-get/70544/8 "2022-11-13T23:44:22Z")

</div>

Ok, your problem is two fold, the initilization of myArray and an 'if' statement.

Make a copy of your existing function node and place it elsewhere on the tab, then put this in the current function node:

```auto
var myArray = context.get("myArray")||[];

var maxdelka = 5;
var soucet = context.get("sum") || 0;
var i = context.get("i") || 0;

myArray.push(msg.bojler);

if ( i <= maxdelka ) { 
// i++;
    soucet += myArray[i];
    i++;
 } 
else {
    i++ ;
    myArray.splice(0 , 1); 
    soucet += myArray[i];
}

msg.prumer = soucet / myArray.length;
context.set("sum", soucet);
msg.soucet = soucet;

msg.delka = myArray.length;
msg.bojler = myArray;

context.set("i", i);
msg.i = i;
context.set("myArray", myArray);

return msg;

```

The first line:  
`var myArray = context.get("myArray")||[];`  
sets the local variable "myArray" to the context value or an empty array.

The second to last line:  
`context.set("myArray", myArray);`  
stores the local value of "myArray" into context.

Now lets look at this code:

```auto
var i = context.get("i") || 0; <= First time thru, 'i' will be 0

myArray.push(msg.bojler); <= This sets myAtrray[0] to the value in msg.bojler

if ( i <= maxdelka ) { <+ maxdelka is '5' and 'i' is 0
// i++; <= this line caused the problem, 'i' becomes 1 
    soucet += myArray[i]; <= myArray[0] has a value but myArray[1] does not
    i++; <= so the incriment of 'i' is done here
 } 
else {
    i++ ;
    myArray.splice(0 , 1); 
    soucet += myArray[i];
}

```

---

<div class="post-metadata">

**Author:** ![vrabi-cv](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/vrabi-cv/32/70654_2.png) [@vrabi-cv](https://discourse.nodered.org/u/vrabi-cv)\
**Post date:** [14 November 2022 21:10 UTC](https://discourse.nodered.org/t/return-data-from-context-get/70544/9 "2022-11-14T21:10:29Z")

</div>

Thank you so much for your help. I made it working, but the "soucet" variable was infinite, so I decided to count only data currently stored in the array for the average value. So finally working functions is like this:

```auto
var myArray = context.get("myArray") || [];
var maxdelka = 6;
var soucet = 0;
var i = context.get("i") || 0;

if (msg.payload == "clear") {
    context.set("i");
    context.set("myArray");
    context.set("soucet");
    return;
}

if (!myArray) {
    node.warn("Set the array on context memory");
    context.set("myArray", []);
    myArray = context.get("myArray");
        
}

myArray.push(msg.bojler);
//node.warn('i='+ i );
//node.warn("myArray=" + myArray);

if ( i <= maxdelka ) { 
    i++;
} 
else {
    i--;
    myArray.splice(0 , 1);
    i++;
}
for (var c = 0; c < myArray.length;) {
    soucet += myArray[c];
    c++;
}
c = 0;

msg.prumer = soucet / myArray.length;
msg.soucet = soucet;
msg.bojler = myArray;

context.set("i", i);
context.set("myArray", myArray);

return msg;

```

---

<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:** [28 November 2022 21:11 UTC](https://discourse.nodered.org/t/return-data-from-context-get/70544/10 "2022-11-28T21:11:08Z")

</div>

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