Help Creating a simple basic yet solid Filter when downloading new articles

[l5oukz89]

// This filter accepts messages whose (title OR content) is on the whitelist AND rejects those whose (title OR content) is on blacklist.
// This filter counts number of characters of the message content and append the title with the length.
// this filter prefixes title with the matched word or words (up to 3 words).
// This filter purges duplicates.
// This filter purges messages that were rejected.

{includes method versus whitelist.some(i => msg.title.indexOf(i) != -1) method ?} (which one is better?)

var or const ? whitelist = ['X', 'Y', 'Z'];
var or const ? blacklist = ['A', 'B', 'C'];

so title should be something like [Length of message content] (mandatory in all cases) + [matched word 1] (mandatory) + [matched word 2] (optional) + [matched word 3] (optional) + [original title] (mandatory)