# Help if not defined variable is accessed
**URL:** https://discourse.nodered.org/t/help-if-not-defined-variable-is-accessed/45377
**Category:** General
**Created:** [8 May 2021 23:27 UTC](https://discourse.nodered.org/t/help-if-not-defined-variable-is-accessed/45377 "2021-05-08T23:27:45Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [8 May 2021 23:27 UTC](https://discourse.nodered.org/t/help-if-not-defined-variable-is-accessed/45377/1 "2021-05-08T23:27:45Z")
Yeah, it is probably easy to do, but for now it escapes me how to do it.
This is the code on a `Function` node:
```auto
var m = msg.month;
m = parseInt(m);
var x = msg.table[m];
msg.payload = x;
return msg;
```
If `msg.table` isn't an array, it throws an error.
How do I get around it and use a _default_ value?
Thanks.
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [8 May 2021 23:37 UTC](https://discourse.nodered.org/t/help-if-not-defined-variable-is-accessed/45377/2 "2021-05-08T23:37:51Z")
Ok, this seems to work:
```auto
var m = msg.month;
m = parseInt(m);
var x;
if (msg.table != undefined)
{
x = msg.table[m];
} else
{
x = 22;
}
msg.payload = x;
return msg;
```
If it isn't defined I get back `22`.
But is there a _neater_ way of doing it?
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [8 May 2021 23:44 UTC](https://discourse.nodered.org/t/help-if-not-defined-variable-is-accessed/45377/3 "2021-05-08T23:44:40Z")
For testing an array you can use `if(Array.isArray(msg.payload) && msg.payload.length)`
This ensures the variable is an array && that it has 1 or more items.
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [8 May 2021 23:50 UTC](https://discourse.nodered.org/t/help-if-not-defined-variable-is-accessed/45377/4 "2021-05-08T23:50:34Z")
Sorry, I don't understand that.
I can only resolve it to:
`if(msg.table.isArray()`
`msg.payload` isn't part of the equation as I see it.
`msg.month` will be set. That is set by the upstream node to set the month value for this month.
It is just the array `msg.table` which may not be set/defined and that is generated upstream too.
I may look at how it is set and do a condition there. But at the end of the day, it needs to be done somewhere and due to recent observations here is as good a place as any to check/test for it being set and if not, set a default value.
Less nodes needed/used.
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [9 May 2021 00:02 UTC](https://discourse.nodered.org/t/help-if-not-defined-variable-is-accessed/45377/5 "2021-05-09T00:02:07Z")
I misread. But essentially is the same.
`if(Array.isArray(msg.table) && msg.table.length)`
The point is that testing for a variable being not undefined does not mean it is an array nor that it has 1 or more elements.
I.e. avoid bugs.
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [9 May 2021 00:07 UTC](https://discourse.nodered.org/t/help-if-not-defined-variable-is-accessed/45377/6 "2021-05-09T00:07:38Z")
Yeah, thanks.
Alas (as you may have noticed/seen) I've been away from NR for a long time.
(Other things happening)
I really do need to keep on top of checking if things I get are (or not) defined and deal with it better than throwing an error.
---
### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [23 May 2021 00:08 UTC](https://discourse.nodered.org/t/help-if-not-defined-variable-is-accessed/45377/7 "2021-05-23T00:08:21Z")
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