# JavaScript debuging

**URL:** <https://www.thethingsnetwork.org/forum/t/javascript-debuging/43688>\
**Category:** V3 Applications\
**Created:** [February 2, 2021, 9:36pm UTC](https://www.thethingsnetwork.org/forum/t/javascript-debuging/43688 "2021-02-02T21:36:44Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![trlafleur](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/trlafleur/32/35697_2.png) [@trlafleur](https://www.thethingsnetwork.org/forum/u/trlafleur)\
**Post date:** [February 2, 2021, 9:36pm UTC](https://www.thethingsnetwork.org/forum/t/javascript-debuging/43688/1 "2021-02-02T21:36:44Z")

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In V2, when I entered a JS function decoder, there was a way to send it test data and a place to see the results from the decoder test…

How do we do this in V3???

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**Author:** ![clv](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/clv/32/46568_2.png) [@clv](https://www.thethingsnetwork.org/forum/u/clv)\
**Post date:** [February 3, 2021, 7:22am UTC](https://www.thethingsnetwork.org/forum/t/javascript-debuging/43688/2 "2021-02-03T07:22:18Z")

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You can’t 😞

You can write your own .js. The down part after  
`// Print the final result:` is not part of the decoder. There you can add testing data (`ttnbytes`) and the following codes.

Of course you must omit `<script>` and `</script>` tags.

[https://js.do/code/557365](https://js.do/code/557365)

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**Author:** ![htdvisser](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/htdvisser/32/45312_2.png) [@htdvisser](https://www.thethingsnetwork.org/forum/u/htdvisser)\
**Post date:** [February 3, 2021, 10:50am UTC](https://www.thethingsnetwork.org/forum/t/javascript-debuging/43688/3 "2021-02-03T10:50:01Z")

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We have some open issues related to this on GitHub:

- [Payload format testing · Issue #2232 · TheThingsNetwork/lorawan-stack · GitHub](https://github.com/TheThingsNetwork/lorawan-stack/issues/2232)
- [Add syntax validation for payload formatters · Issue #3442 · TheThingsNetwork/lorawan-stack · GitHub](https://github.com/TheThingsNetwork/lorawan-stack/issues/3442)

If this is important to you, you can add a 👍 on those issues. The team uses those 👍's to prioritize what we’re working on. Also, if you’re interested in contributing this feature, please leave a comment on the GitHub issue.

![Screen Shot 2021-02-03 at 11.45.49](https://www.thethingsnetwork.org/forum/uploads/default/original/3X/4/c/4ca23948dd6b8d247056f35f1baef030d5c4892e.png)