JSFiddle - React, Tailwind, and code Playground

JavaScript

function isEqual1() {
    var val = arguments[0],
        equal = true;
    for (var i = 0; i < arguments.length; i++) {
        equal = (arguments[i] === val);
        if (!equal) return false;
    }
    return equal;
}

function isEqual2() {
    var args = Array.prototype.slice.call(arguments, 0);
    var equal = args.join(',').replace(new RegExp(args[0], "ig"), '').replace(/,/g, "");
    return equal.length == 0;
}

console.log(isEqual1(1, true, false, "xyz"));
console.log(isEqual1(true, true, true, true));
console.log(isEqual2(true, 123, true, true));
console.log(isEqual2(true, true, true, true));