first non repeating char

first non repeating char.js

// default: 5.187ms (nevermind)
function f(s) {
    let arr = Array.apply(0, { length: 26 }).map((c) => 0)
    for (let c of s.split('')) arr[c.charCodeAt(0) - 'a'.charCodeAt(0)]++;
    for (let c of s.split('')) {
        if (arr[c.charCodeAt(0) - 'a'.charCodeAt(0)] == 1) return c;
    }
    console.log(arr)
    return '_'
}
console.log(
    f('')
);


// default: 10.70ms (Tarek Hesham#0001)
const char = (str) => {
    for (let i = 0; i < str.length; i++) {
        if (str.split("").filter(x => x == str[i]).length == 1) return str[i];
    };
};
console.log(char(""));