# Can not make Javascript encodeDownlink payload formatter to work

**URL:** <https://www.thethingsnetwork.org/forum/t/can-not-make-javascript-encodedownlink-payload-formatter-to-work/48322>\
**Category:** V3 Console\
**Created:** [June 1, 2021, 8:03am UTC](https://www.thethingsnetwork.org/forum/t/can-not-make-javascript-encodedownlink-payload-formatter-to-work/48322 "2021-06-01T08:03:53Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![robertlie](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/robertlie/32/37681_2.png) [@robertlie](https://www.thethingsnetwork.org/forum/u/robertlie)\
**Post date:** [June 1, 2021, 8:03am UTC](https://www.thethingsnetwork.org/forum/t/can-not-make-javascript-encodedownlink-payload-formatter-to-work/48322/1 "2021-06-01T08:03:53Z")

</div>

I am working on a YouTube tutorial about Javascript payload formatters in the TTS CE console.  
I don’t seem to make a simple encodeDownlink payload formatter to work.  
The payload formatter is just a demo.  
Can someone tell me what is wrong with my encodeDownlink function?

JSON payload:

```
{
       "data": {
          "aa": 4
       }
    }
```

Downlink formatter:

```
function encodeDownlink(input) {
    	var bytes = [1, 2, 3, input.data.aa];
    	return {
    		bytes: bytes
    	};
    }
```

The payload output is:  
01 02 03 00

But i expected as result: 01 02 03 04

![forum](https://www.thethingsnetwork.org/forum/uploads/default/original/3X/a/7/a79e2e19bc8d0c8235618ca5e5055c9a429585fb.png)

---

<div class="post-metadata">

**Author:** ![robertlie](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/robertlie/32/37681_2.png) [@robertlie](https://www.thethingsnetwork.org/forum/u/robertlie)\
**Post date:** [June 3, 2021, 2:36pm UTC](https://www.thethingsnetwork.org/forum/t/can-not-make-javascript-encodedownlink-payload-formatter-to-work/48322/2 "2021-06-03T14:36:16Z")

</div>

Got the answer! This is the solution:  
The json payload should be {“aa”: 4}