# Substring() error - how to get around it?
**URL:** https://discourse.nodered.org/t/substring-error-how-to-get-around-it/56441
**Category:** General
**Created:** [11 January 2022 05:08 UTC](https://discourse.nodered.org/t/substring-error-how-to-get-around-it/56441 "2022-01-11T05:08:20Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [11 January 2022 05:08 UTC](https://discourse.nodered.org/t/substring-error-how-to-get-around-it/56441/1 "2022-01-11T05:08:20Z")
I hope this is the part of the code which is throwing an error.
```auto
var led = parseInt(led_msg.substring(4,5)) || 0;
```
How can I wrap this so if it doesn't _exist_ that it gives a `0`.
---
### Author:  [@UnborN](https://discourse.nodered.org/u/UnborN)
#### Post date: [11 January 2022 05:36 UTC](https://discourse.nodered.org/t/substring-error-how-to-get-around-it/56441/2 "2022-01-11T05:36:30Z")
Hi Andrew .. maybe you can try to check if `led_msg` has a truthy value (if it exists)
before trying to substring or parseInt it.
```auto
var led = led_msg ? parseInt(led_msg.substring(4,5)) : 0
```
The ? and : is just a funcy way of writing if statements in one line
Which translates to
`led_msg ?` does led\_msg have value ?
if yes do `parseInt(led_msg.substring(4,5))`
if not `:` set to `0`
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [11 January 2022 05:46 UTC](https://discourse.nodered.org/t/substring-error-how-to-get-around-it/56441/3 "2022-01-11T05:46:33Z")
Thanks.
That magic is beyond me and my knowledge.
So if I put that line in, in place of the existing one, all should be ok?
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### Author:  [@UnborN](https://discourse.nodered.org/u/UnborN)
#### Post date: [11 January 2022 05:57 UTC](https://discourse.nodered.org/t/substring-error-how-to-get-around-it/56441/4 "2022-01-11T05:57:15Z")
> [@Trying\_to\_learn](#):
>
> in place of the existing one
yes .. replace it, fingers crossed that thats the problem ..
it does more or less the same with the only difference that it checks first if `led_msg` has a value.
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [11 January 2022 06:00 UTC](https://discourse.nodered.org/t/substring-error-how-to-get-around-it/56441/5 "2022-01-11T06:00:47Z")
Thanks.
That's fixed **THAT** problem. Now on to the ever growing list of others. 😉
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### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [25 January 2022 06:01 UTC](https://discourse.nodered.org/t/substring-error-how-to-get-around-it/56441/6 "2022-01-25T06:01:22Z")
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