Doc Merge: filtering records based on what a field contains

Hi,

I would like to create a document which displays all the notes of a certain account which contain a certain word in their description, or in their tags.

I couldn't find the syntax to create a conditional rule based on the content of the field. Following the appendix, I've tried with 

{#notes}{if (description.filter(item=>item.includes("bal")).length>0)}{name}

{date_entered}

{created_by_name.user_name}

{description}{endif}

{tag}{/notes}

but I get the error "description.filter is not a function"

I'm not sure to understand the syntax needed.

Could you help me?

Thanks,

Raul