# How the Dec to hex? And the node can show warn or errer information?
**URL:** https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739
**Category:** General
**Created:** [28 June 2021 09:56 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739 "2021-06-28T09:56:39Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@jlian168](https://discourse.nodered.org/u/jlian168)
#### Post date: [28 June 2021 09:56 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/1 "2021-06-28T09:56:40Z")
Dear All :
'''
if(msg.payload\>5000)
{
//show warn or error : The number is too large...
return null;
}
else
{
//Here is Dec to Hex...
return msg;
}
'''
Thank u.
---
### Author:  [@jbudd](https://discourse.nodered.org/u/jbudd)
#### Post date: [28 June 2021 10:17 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/2 "2021-06-28T10:17:49Z")
Hi jlian168. Here is a simple example.
What is your native language?
Are you a student?
```auto
[{"id":"aeecd730.670b08","type":"function","z":"283b54b6.9ab9ac","name":"","func":"if (msg.payload > 5000) {\n node.warn (\"Number too large: \" + msg.payload);\n}\nelse {\n msg.payload = msg.payload.toString(16);\n return msg;\n}","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":370,"y":260,"wires":[["6379264e.fa09d"]]},{"id":"6379264e.fa09d","type":"debug","z":"283b54b6.9ab9ac","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":550,"y":260,"wires":[]},{"id":"50f03a1.64ac2c4","type":"inject","z":"283b54b6.9ab9ac","name":"","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"4999","payloadType":"num","x":190,"y":240,"wires":[["aeecd730.670b08"]]},{"id":"5e9e6062.a86f28","type":"inject","z":"283b54b6.9ab9ac","name":"","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"5001","payloadType":"num","x":190,"y":280,"wires":[["aeecd730.670b08"]]}]
```
---
### Author:  [@jlian168](https://discourse.nodered.org/u/jlian168)
#### Post date: [28 June 2021 10:33 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/3 "2021-06-28T10:33:36Z")
Dear jbudd :
1. My native language is chinese.
2. Thanks for ur code and I think ur code is to string not HEX,
And I hope the warn can show in UI html But I dont know how...
Thank u very much.
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [28 June 2021 11:00 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/4 "2021-06-28T11:00:02Z")
Where do you want to see the warning? node red editor? As a popup on the dashboard or where?
What do you mean by hex if you do not mean a string with the hex characters? What do want to do with it?
---
### Author:  [@jbudd](https://discourse.nodered.org/u/jbudd)
#### Post date: [28 June 2021 12:02 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/5 "2021-06-28T12:02:28Z")
This flow accepts a decimal number (as a string) on the UI.
It converts it to a number and then to (a string representation of) Hex.
eg it converts 423 to 1a7.
Surely the only way that Hex can be displayed is as a string?
Your English is much much better than my Chinese!
Are you a student?
```auto
[{"id":"aeecd730.670b08","type":"function","z":"283b54b6.9ab9ac","name":"","func":"if (msg.payload > 5000) {\n msg.payload = \"Number too large: \" + msg.payload;\n}\nelse {\n msg.payload = Number(msg.payload).toString(16);\n}\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":280,"y":260,"wires":[["9c16de2f.ff852"]]},{"id":"9c16de2f.ff852","type":"ui_text","z":"283b54b6.9ab9ac","group":"a6e358b.672ffa8","order":2,"width":"3","height":"1","name":"","label":"Hex is 0x","format":"{{msg.payload}}","layout":"row-left","x":440,"y":260,"wires":[]},{"id":"bfe545cb.c1af4","type":"ui_text_input","z":"283b54b6.9ab9ac","name":"","label":"Type a number ","tooltip":"","group":"a6e358b.672ffa8","order":1,"width":"3","height":"1","passthru":true,"mode":"text","delay":300,"topic":"topic","topicType":"msg","x":100,"y":260,"wires":[["aeecd730.670b08"]]},{"id":"a6e358b.672ffa8","type":"ui_group","name":"Demo","tab":"4e528085.a1bfa","order":1,"disp":true,"width":"20","collapse":false},{"id":"4e528085.a1bfa","type":"ui_tab","name":"Demo","icon":"dashboard","order":2,"disabled":false,"hidden":false}]
```
---
### Author:  [@jlian168](https://discourse.nodered.org/u/jlian168)
#### Post date: [29 June 2021 09:14 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/6 "2021-06-29T09:14:41Z")
Dear jbudd :
Im office worker.And I hv 3 question at Pics & below :
1. The Dec to Hex is not correct?
2. How to only show error information at text1?
3. How can let switch when start is action at text?
Thank u.
---
### Author:  [@E1cid](https://discourse.nodered.org/u/E1cid)
#### Post date: [29 June 2021 10:33 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/7 "2021-06-29T10:33:05Z")
You are over writting msg payload eg
```auto
let array=[0]
msg.payload = Number(msg.payload).toString(16);
array[1] = msg.payload << 8; //unsure why you are doing this
array[2]= msg.payload&0xff; // unsure why you are doing this
msg.payload =array;
return msg;
```
produces
while
```auto
let array=[0]
array[0] = Number(msg.payload).toString(16);
array[1] = msg.payload << 8;
array[2]= msg.payload&0xff;
msg.payload = array;
return msg;
```
produces
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [29 June 2021 10:39 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/8 "2021-06-29T10:39:49Z")
What _exactly_ are you trying to get out of the function? Give us a sample input and tell us what output you want.
---
### Author:  [@jbudd](https://discourse.nodered.org/u/jbudd)
#### Post date: [29 June 2021 11:21 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/9 "2021-06-29T11:21:27Z")
2 How to only show error information at text1?
Use a switch node (from the "function" section of the palette, not a UI switch) to send the msg to different UI elements depending on it's value or datatype.
3 How can let switch when start is action at text?
I do not understand the question.
But you can change the switch state either by clicking on it in the UI or by injecting a message into it.
```auto
[{"id":"25bac54e.c332e2","type":"ui_switch","z":"283b54b6.9ab9ac","name":"","label":"switch","tooltip":"","group":"a6e358b.672ffa8","order":5,"width":"2","height":"2","passthru":true,"decouple":"false","topic":"topic","topicType":"msg","style":"","onvalue":"on","onvalueType":"str","onicon":"","oncolor":"","offvalue":"off","offvalueType":"str","officon":"","offcolor":"","animate":false,"x":510,"y":380,"wires":[["96469f52.d48928"]]},{"id":"d3165a0b.4d9f78","type":"inject","z":"283b54b6.9ab9ac","name":"Inject the switch ON payload","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"on","payloadType":"str","x":280,"y":360,"wires":[["25bac54e.c332e2"]]},{"id":"21397442.893e44","type":"inject","z":"283b54b6.9ab9ac","name":"Inject the switch OFF payload","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"off","payloadType":"str","x":280,"y":400,"wires":[["25bac54e.c332e2"]]},{"id":"96469f52.d48928","type":"debug","z":"283b54b6.9ab9ac","name":"","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"payload","targetType":"msg","statusVal":"payload","statusType":"auto","x":690,"y":380,"wires":[]},{"id":"eaf47ee1.d2862","type":"inject","z":"283b54b6.9ab9ac","name":"Anything else has no effect","props":[{"p":"topic","v":"0","vt":"num"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","x":270,"y":440,"wires":[["25bac54e.c332e2"]]},{"id":"a6e358b.672ffa8","type":"ui_group","name":"Demo","tab":"4e528085.a1bfa","order":1,"disp":true,"width":"20","collapse":false},{"id":"4e528085.a1bfa","type":"ui_tab","name":"Demo","icon":"dashboard","order":2,"disabled":false,"hidden":false}]
```
---
### Author:  [@jlian168](https://discourse.nodered.org/u/jlian168)
#### Post date: [30 June 2021 02:26 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/10 "2021-06-30T02:26:35Z")
Dear All Sir : Thanks for ur reply...
I hv another some question at Pics and below :
/_-------------------------------------------------------------------------------------------_/
1.
1.1. : Why show "1388" not 1388?
msg.payload = Number(msg.payload).toString(16);
no2\_array[1]=msg.payload;
1.2. : Why is 355328 not 13?
no2\_array[2]=msg.payload\<\<8;
1.3. : Why is 108 not 88?
no2\_array[3]=msg.payload&0xFF;
/_-------------------------------------------------------------------------------------------_/
2.
I want use a button, When I press the button then the function value
is send to debug window.
And now I press the button the is show "3c74b97f.ec90e6"! Why?
How to do Show it right?
/_-------------------------------------------------------------------------------------------_/
Thank u.
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [30 June 2021 06:19 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/11 "2021-06-30T06:19:45Z")
> [@jlian168](#):
>
> 1.1. : Why show "1388" not 1388?
> msg.payload = Number(msg.payload).toString(16);
> no2\_array[1]=msg.payload;
>
> 1.2. : Why is 355328 not 13?
> no2\_array[2]=msg.payload\<\<8;
>
> 1.3. : Why is 108 not 88?
> no2\_array[3]=msg.payload&0xFF;
Because you call toString then try to do bitshift operations on a string.
---
### Author:  [@jlian168](https://discourse.nodered.org/u/jlian168)
#### Post date: [30 June 2021 06:28 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/12 "2021-06-30T06:28:07Z")
Dear Steve-Mcl :
So how to become Hex not Str?
Thank u.
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [30 June 2021 06:54 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/13 "2021-06-30T06:54:00Z")
> [@jlian168](#):
>
> So how to become Hex not Str?
Hexadecimal is just a number in base 16. The underlying number is the same.
So do all you math in decimal then ONLY when you want to display it should you convert to hexadecimal
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [30 June 2021 06:54 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/14 "2021-06-30T06:54:52Z")
> [@jlian168](#):
>
> So how to become Hex not Str?
As I asked before, tell us an example of an input and what you want to convert that to, and why you want to do it.
---
### Author:  [@jlian168](https://discourse.nodered.org/u/jlian168)
#### Post date: [30 June 2021 07:08 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/15 "2021-06-30T07:08:07Z")
Dear Colin :
1. Input is Number(I think is Dec).
2. In the function I want convert Dec to Hex.(But the resault is String!How to do become Hex?)
3. Last I hope can press button then output show is Hex.(But button cant, How to do or use another node?)
Thank u.
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [30 June 2021 07:21 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/16 "2021-06-30T07:21:32Z")
So, converting to Hexadecimal will ALWAYS result in a string (because hexadecimal contains letters) - there is no way around this. BUT. Decimal and Hexadecimal (and octal and binary) are all just representations of the same number. My point is - stick with decimal for the maths THEN at the last moment, just before display, convert it to the format you wish to see.
This is what happens when you convert to hex string ...
This is what happens when you leave the number as decimal & convert at the end...
* * *
## Can you please tell us an...
- An example `msg.payload` input number (e.g. `4920`)
- what you expect to see at the end of your function (e.g. `[???, ???, ???]`
* * *
NOTES:
- Arrays are zero based not 1 based
- Why do you put the answers into an array anyway? They would be far better/easier in an object e.g...
```auto
result = {};
originalValue = msg.payload;
result.original = originalValue;
result.shifted = originalValue << 8;
result.anded = originalValue & 0xFF;
result.originalHex = originalValue.toString("16");
result.shiftedHex = result.shifted.toString("16");
result.andedHex = result.andedHex.toString("16");
msg.payload = result;
```
---
### Author:  [@jlian168](https://discourse.nodered.org/u/jlian168)
#### Post date: [30 June 2021 07:43 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/17 "2021-06-30T07:43:54Z")
Dear Steve-Mcl :
ok, I see, look at pic,
1. so "1388" and"13 "and"88" are still String not Hex? if its String then how to become Hex?
2. Last I hope can press button(maybe another node can be) then output to debug window, I dont know how to do?
Thank u.
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [30 June 2021 07:51 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/18 "2021-06-30T07:51:39Z")
> [@jlian168](#):
>
> so "1388" and"13 "and"88" are still String not Hex?
`'1388'` **IS** hexadecimal equivalent of `4920`
PROOF...
And as I said before
> [@Steve-Mcl](#):
>
> Hexadecimal will ALWAYS result in a string (because hexadecimal contains letters)
* * *
As I asked before...
> [@Steve-Mcl](#):
>
> ## Can you please tell us an...
>
> - An example `msg.payload` input number (e.g. `4920` )
> - what you expect to see at the end of your function (e.g. `[???, ???, ???]`
(Google translation)
你能告诉我们一个...
- 示例 `msg.payload` 输入数字（例如 `4920`）
- 您希望在函数结束时看到的内容（例如`[???, ???, ???]`
---
### Author:  [@jlian168](https://discourse.nodered.org/u/jlian168)
#### Post date: [30 June 2021 07:54 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/19 "2021-06-30T07:54:45Z")
Dear Steve-Mcl :
ok, Sorry.
5000(Dec)=1388(Hex)
Now is ["1388","13","88"]
I hope is [1388,13,88]
Thank u.
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [30 June 2021 08:01 UTC](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739/20 "2021-06-30T08:01:56Z")
> [@jlian168](#):
>
> 5000(Dec)=1388(Hex)
>
> Now is ["1388","13","88"]
> I hope is [1388,13,88]
So you can easily convert string to number using `Number("1388")`
# BUT
If your incoming msg.payload is `4990` then the hex will be `137E`
So you **cannot** turn `137E` into a number
[Next page](https://discourse.nodered.org/t/how-the-dec-to-hex-and-the-node-can-show-warn-or-errer-information/47739.md?page=2)