Intersection of characters in two strings

Question

I have an object with strings in it.

filteredStrings = {search:\'1234\', select:\'1245\'}

I want to return

\'124\'
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Answer 1

Convert one of the strings (search) to a RegExp character set. Use the RegExp with String#match on the other string (select).

Note: Unlike lodash's intersection, the result characters are not unique, so for example 4 can appear twice.

var filteredStrings = {search:'1234', select:'124561234'}

var result = (filteredStrings.select.match(new RegExp('[' + filteredStrings.search + ']', 'g')) || []).join('');

console.log(result);