remove duplicate string

remove_duplicate_str.js

const fs = require("fs");
const file = fs.readFileSync("str.txt", "utf-8");
const removeDuplicateChar = (str) => {
    return str.filter((v, idx) => {
        const f = str.lastIndexOf(v);;
        if (f && idx !== f) {
            str.splice(f, 1);
        }
        return v;
    });
}

console.log(removeDuplicateChar(file.split("")))