# Function-node freezes whole node-red

**URL:** https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028
**Category:** General
**Tags:** function-node
**Created:** [10 December 2021 22:17 UTC](https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028 "2021-12-10T22:17:47Z")
**Posts on this page:** 10
**Page:** 1

<div class="post-metadata">

### Author: ![hutje](https://avatars.discourse-cdn.com/v4/letter/h/43a26b/32.png) [@hutje](https://discourse.nodered.org/u/hutje)
#### Post date: [10 December 2021 22:17 UTC](https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028/1 "2021-12-10T22:17:47Z")

</div>

Hi

I am currently working on a way to make a hex buffer out of various hex stings.  
A microcontroller (ESP32) will be using those hex values as values to compare an input with.  
I want to keep the message over MQTT as small as possible. Eventually the size will be 50KB.  
The following flow consists of:  
-A working function where a few hexstrings will be converted to an integer.  
-A not working function where node-red freezes completely... (Use at own risk).

I do not get why this makes it crash...

```auto
[{"id":"1b78ffdb.adbf5","type":"tab","label":"Flow 1","disabled":false,"info":""},{"id":"1cfe95.33e3216c","type":"inject","z":"1b78ffdb.adbf5","name":"FREEZE","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"{\"package\":{\"allowedTokens\":[\"ffffffff\",\"feffffff\",\"fdffffff\",\"f0ffff\",\"ffffffff\",\"0fffffff\",\"ffff\"]}}","payloadType":"json","x":120,"y":340,"wires":[["ea6f02c.7752b"]]},{"id":"ea6f02c.7752b","type":"function","z":"1b78ffdb.adbf5","name":"","func":"var arrayIndex = [];\nvar arrayDB = [];\n\nfor(var i = 0; i<msg.payload.package.allowedTokens.length; i++){\n \n if (msg.payload.package.allowedTokens[i].length % 2) {\n msg.payload.package.allowedTokens[i] = '0' + msg.payload.package.allowedTokens[i];\n }\n var index = 0;\n for(var j = 0; j<msg.payload.package.allowedTokens[i].length; j+2){\n var subStr = msg.payload.package.allowedTokens[i].substring(j, j + 2);\n arrayDB[j] = parseInt(subStr,16);\n index++;\n }\n arrayIndex[i] = index;\n \n}\n// return bufferAllowedTokens;\n// }\nmsg.payload=\"\";\nmsg.payload.request = {\"request\": \"Test\"};\nmsg.payload.package = {\"allowedTokens\": arrayDB};\nmsg.payload.package = {\"arrayIndex\": arrayIndex};\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":360,"y":340,"wires":[["bfff5362.cab5b"]]},{"id":"bfff5362.cab5b","type":"debug","z":"1b78ffdb.adbf5","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":690,"y":340,"wires":[]},{"id":"9af8572.e34dea8","type":"function","z":"1b78ffdb.adbf5","name":"","func":"for(var i = 0; i<msg.payload.package.allowedTokens.length; i++){\n // while(msg.payload.package.allowedTokens[i].length != 16){\n \n // }\n msg.payload.package.allowedTokens[i] = parseInt(msg.payload.package.allowedTokens[i],16);\n}\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":360,"y":140,"wires":[["5ab00037.f7b44"]]},{"id":"48b697fe.837ee8","type":"inject","z":"1b78ffdb.adbf5","name":"","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"{\"package\":{\"allowedTokens\":[\"049b26870ec9b92c\",\"c704a48b079c8db9\",\"d267e8f255b65fee\",\"66ca6022885a74e1\",\"3dce7df596f567a0\",\"64ab45796b1a83da\",\"dccf0b13c7dd9098\",\"8c3b38588c2ba11b\",\"aaab4873fe0c94df\",\"7ac8a016\",\"d9fe13b4\",\"03350f2a\"]}}","payloadType":"json","x":110,"y":140,"wires":[["9af8572.e34dea8"]]},{"id":"5ab00037.f7b44","type":"debug","z":"1b78ffdb.adbf5","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":670,"y":140,"wires":[]},{"id":"5788ce3b.073eb","type":"comment","z":"1b78ffdb.adbf5","name":"Working without substring","info":"","x":150,"y":80,"wires":[]},{"id":"bd8f92a6.36318","type":"comment","z":"1b78ffdb.adbf5","name":"[FREEZES Node-Red] Not working with substring","info":"","x":220,"y":280,"wires":[]}]

```

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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: [10 December 2021 22:20 UTC](https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028/2 "2021-12-10T22:20:51Z")

</div>

You are likely creating an endless loop. Use `node.warn(?)` to check your for loop variables are valid and as expected.

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<div class="post-metadata">

### Author: ![hutje](https://avatars.discourse-cdn.com/v4/letter/h/43a26b/32.png) [@hutje](https://discourse.nodered.org/u/hutje)
#### Post date: [10 December 2021 22:21 UTC](https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028/3 "2021-12-10T22:21:50Z")

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Node-Red freezes completely. I can't do anything...

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<div class="post-metadata">

### Author: ![knolleary](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/knolleary/32/3_2.png) [@knolleary](https://discourse.nodered.org/u/knolleary)
#### Post date: [10 December 2021 22:23 UTC](https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028/4 "2021-12-10T22:23:43Z")

</div>

You can start Node-RED in safe mode by adding the ` --safe` argument to the node-red command.

This will start Node-RED without running your flows. You can then edit the function node to remove the loop and deploy the change to start it running

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<div class="post-metadata">

### Author: ![hutje](https://avatars.discourse-cdn.com/v4/letter/h/43a26b/32.png) [@hutje](https://discourse.nodered.org/u/hutje)
#### Post date: [10 December 2021 22:25 UTC](https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028/5 "2021-12-10T22:25:44Z")

</div>

Yes, but I manually trigger the function. So I can do `node-red-stop` and `node-red-start` and it runs again.  
But I can't figure out why Node-Red freezes when it runs that function.

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<div class="post-metadata">

### Author: ![knolleary](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/knolleary/32/3_2.png) [@knolleary](https://discourse.nodered.org/u/knolleary)
#### Post date: [10 December 2021 22:37 UTC](https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028/6 "2021-12-10T22:37:40Z")

</div>

I'm not near my laptop to import the whole flow. Can you share just the function code so we can look at it directly?

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<div class="post-metadata">

### Author: ![hutje](https://avatars.discourse-cdn.com/v4/letter/h/43a26b/32.png) [@hutje](https://discourse.nodered.org/u/hutje)
#### Post date: [10 December 2021 22:44 UTC](https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028/7 "2021-12-10T22:44:19Z")

</div>

It seems JSfiddle has also a hard time running this piece...

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/e/8/e8bc109c6ef5b3adeaaf12d9e470db56a85f72ec.png)

```auto
var arrayIndex = [];
var arrayDB = [];

for(var i = 0; i<msg.payload.package.allowedTokens.length; i++){
    
    if (msg.payload.package.allowedTokens[i].length % 2) {
        msg.payload.package.allowedTokens[i] = '0' + msg.payload.package.allowedTokens[i];
        node.warn(msg.payload.package.allowedTokens[i]);
        
    }
    var index = 0;
    for(var j = 0; j<msg.payload.package.allowedTokens[i].length; j+2){
        var subStr = msg.payload.package.allowedTokens[i].substring(j, j + 2);
        node.warn(subStr);
        arrayDB[j] = parseInt(subStr,16);
        node.warn(arrayDB[j]);
        index++;
    }
    arrayIndex[i] = index;
            
}

msg.payload="";
msg.payload.request = {"request": "Test"};
msg.payload.package = {"allowedTokens": arrayDB};
msg.payload.package = {"arrayIndex": arrayIndex};
return msg;

```

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<div class="post-metadata">

### Author: ![knolleary](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/knolleary/32/3_2.png) [@knolleary](https://discourse.nodered.org/u/knolleary)
#### Post date: [10 December 2021 22:56 UTC](https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028/8 "2021-12-10T22:56:49Z")

</div>

> [@hutje](#):
>
> ```auto
> for(var j = 0; j<msg.payload.package.allowedTokens[i].length; j+2){
>         
> 
> ```

`j+2` should be `j+=2`

Otherwise you're not incrementing j at all and it'll get stuck in that for loop forever.

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<div class="post-metadata">

### Author: ![hutje](https://avatars.discourse-cdn.com/v4/letter/h/43a26b/32.png) [@hutje](https://discourse.nodered.org/u/hutje)
#### Post date: [10 December 2021 23:00 UTC](https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028/9 "2021-12-10T23:00:37Z")

</div>

🤦‍♂️ 🤦‍♂️  
I think this means I should go to bed then 😅

Thanks for the help!

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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: [24 December 2021 23:01 UTC](https://discourse.nodered.org/t/function-node-freezes-whole-node-red/55028/10 "2021-12-24T23:01:30Z")

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