Unique characters: Difference between revisions

Or, folding the strings (with Array.reduce) down to a hash of character frequencies:

<lang javascript>(() => {

"use strict";

// uniqueChars :: [String] -> [Char]

const uniqueChars = ws =>

Object.entries(

ws.reduce(

(dict, w) => [...w].reduce(

(a, c) => Object.assign({}, a, {

[c]: 1 + (a[c] || 0)

}),

dict

), {}

)

)

.flatMap(

([k, v]) => 1 === v ? (

[k]

) : []

);

// ---------------------- TEST -----------------------

const main = () =>

uniqueChars([

"133252abcdeeffd", "a6789798st", "yxcdfgxcyz"

]);

return JSON.stringify(main());

})();</lang>

{{Out}}

<pre>["1","5","6","b","s","t","g","z"]</pre>