# How to add custom functions to toolbox arrays
**URL:** https://forum.makecode.com/t/how-to-add-custom-functions-to-toolbox-arrays/43939
**Category:** PXT
**Created:** [May 11, 2026, 2:50pm UTC](https://forum.makecode.com/t/how-to-add-custom-functions-to-toolbox-arrays/43939 "2026-05-11T14:50:10Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@THEb0nny](https://forum.makecode.com/u/THEb0nny)
#### Post date: [May 11, 2026, 2:50pm UTC](https://forum.makecode.com/t/how-to-add-custom-functions-to-toolbox-arrays/43939/1 "2026-05-11T14:50:10Z")
How can I add my functions to the arrays namespace?
I created functions in an extension and placed them in the arrays namespace. But they don’t show up in the toolbox’s arrays section. I tried placing them in subcategory, but nothing happens. Is there a way to solve this?
namespace arrays {
```auto
/**
```
```
\* Поиск наиболее часто встречающегося числа в массиве - мода.
\* Если массив был пустым, то вернёт null.
\* @param numbers массив с числами
\*/
//% blockId="Mode"
//% block="mode of $numbers array"
//% weight="89"
//% blockNamespace="custom"
//% subcategory="Ext"
//% group="Statistics"
export function mode(numbers: number\[\]): number {
if (numbers.length === 0) return null;
numbers.sort((a, b) => a - b);
let maxCount = 0, currentCount = 1;
let currentNum = numbers\[0\], mostFrequentNum = numbers\[0\];
for (let i = 1; i < numbers.length; i++) {
if (numbers\[i\] === currentNum) currentCount++;
else {
if (currentCount > maxCount) {
maxCount = currentCount;
mostFrequentNum = currentNum;
}
currentNum = numbers\[i\];
currentCount = 1;
}
}
if (currentCount > maxCount) mostFrequentNum = currentNum;
return mostFrequentNum;
}
```
}
---
### Author:  [@NeverStopTheCoder](https://forum.makecode.com/u/NeverStopTheCoder)
#### Post date: [May 12, 2026, 3:38am UTC](https://forum.makecode.com/t/how-to-add-custom-functions-to-toolbox-arrays/43939/2 "2026-05-12T03:38:49Z")
for a custom extension you just I think have to have the namespace be the exact same name maybe its Arrays,array,Array,Arrays so just figure out which one name your namespace that and it should work
---
### Author:  [@THEb0nny](https://forum.makecode.com/u/THEb0nny)
#### Post date: [May 12, 2026, 5:37pm UTC](https://forum.makecode.com/t/how-to-add-custom-functions-to-toolbox-arrays/43939/3 "2026-05-12T17:37:46Z")
I’ve already tried all of this. I could access my functions using the specified namespace in the JS code. But it still doesn’t show up in the standard arrays category in the toolbox.