# @richard what the heck is this **URL:** https://forum.makecode.com/t/richard-what-the-heck-is-this/42112 **Category:** Help **Created:** [February 12, 2026, 5:58pm UTC](https://forum.makecode.com/t/richard-what-the-heck-is-this/42112 "2026-02-12T17:58:28Z") **Posts on this page:** 1 **Showing post:** 5
### Author: ![WoofWoof](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/woofwoof/32/32523_2.png) [@WoofWoof](https://forum.makecode.com/u/WoofWoof) #### Post date: [February 13, 2026, 6:09pm UTC](https://forum.makecode.com/t/richard-what-the-heck-is-this/42112/5 "2026-02-13T18:09:43Z")
The thing is that you can’t actually _use_ these arrays. For example, if you created an array of a number and some text, it would be of type “string | number” which you can’t really do anything with (in blocks). Unless you are type checking it, which doesn’t exist in blocks, it will cause an error… wait… ok new [pxt-JavaScript-extras](https://forum.makecode.com/t/making-an-extension-for-every-javascript-exclusive-feature-i-can-think-of/36766) update, I’ve added the “typeof” block. You can now do type checking in blocks, have fun. Nope. No fun to be had here. The compiler still complains if you use the block I made, sorry. You would have to go into JavaScript, type “typeof”, and then switch back to make the compiler happy. Very sad. --- _[View the full topic](https://forum.makecode.com/t/richard-what-the-heck-is-this/42112)._