JSFiddle - React, Tailwind, and code Playground

by jfriend00

JavaScript

function countUniqueChars(testVal) {
    var index = {};
    var ch, cnt = 0;
    for (var i = 0; i < testVal.length; i++) {
        ch = testVal.charAt(i);
        if (!(ch in index)) {
            index[ch] = true;
            ++cnt;
        }
    }
    return(cnt);
}

function hasFourUniqueChars(testVal) {
    return(countUniqueChars(testVal) >= 4);
}

alert(countUniqueChars("test1"));