i have some issues when i try to conver php code to javascript with simple operator

Depending from who/where comes from this code, but a simple “&” is a mask function.

It’s is useful in case you want to mask a first var by a second like so :

"11001010" & "11110000"  // Will return 11000000

I can’t explain you in some lines, so you can google it

But i guess this make no sense on alphabet, so your code is probably invalid.