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'

I know that I can turn it into an array and then loop through each value and test if that value in inside of the other string, but I'm looking for an easier way to do this. Preferably with Lodash.

I've found _.intersection(Array,Array) but this only works with Arrays.

https://lodash.com/docs#intersection

I want to be able to do this without having to convert the object to an array and then loop through each value because this is going to be potentially holding a lot of information and I want it to work as quickly as possible.

Thank you for you help.

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);