A Javascript regex to filter all dutch cellphone numbers from a particular text and filter for uniqueness. Works for no mathces, one match and multiple matches.

filter06.js

var text = `
the text containing a couple of 0612345678 numbers. like so: 0612345678 and so:
0687654321
and
another
example
0674839201
`;

// Approach one: returns an ES6 Set.
new Set(text.match(/06[0-9]{8}/gm)); //=> Set(3) {"0612345678", "0687654321", "0674839201"}

// Approach two: returns an array only containing unique values.
(text.match(/06[0-9]{8}/gm) || []).filter((e,i,a) => a.indexOf(e) == i); //=> ["0612345678", "0687654321", "0674839201"]

Shell approach to getting unique cellphone numbers from any file (here a .log file), sorted and filtered for unique ones.

$ < [FILENAME].log grep -oP '06[0-9]{8}' | sort --unique