In spacemacs you can spc s p to find keywords within your project, in my case Spacemacs uses grep as it is the first search tool it finds according to its dotspacemacs-search-tools configuration.
My problem is that in projects where I have a folder with compiled javascript, Helm/Grep looks for said keyword within those folders, making Spacemacs either freeze or sometimes crash, how can I tell Helm (within the context of Spacemacs) to ignore such folders?
Here is an example of how it looks like:

I've tried looking for some clues in the help section of (C-c ?) but haven't found anything yet.
Any help is appreciated :)
Edit/Update: Bahman's answer is in fact correct. Note however that in my case I had to also include a directory inside "projectile-globally-ignored-directories" configuration in order to work:

