Javascript deobfuscation or tell me how they did it?

Question

JavaScript

Hello. On the site, javascript is encoded in some weird way: [][(![]+[])[+[]]+([![]]+[])[+!+[]+[+ []]]+(![]+[])
I did not insert all the code, a large number of characters. Can you tell me how to decode it? Or throw a link online decoding. Does anyone know how it was coded?
Link - look in the html code line 340 and 341

Answer 1

Encoder - www.jsfuck.com
Decoder - https://enkhee-osiris.github.io/Decoder-JSFuck/