function scrambler(str) {
    var thingy = str.textContent;
    var that = thingy.split("");
    var len = that.length;
    var thatChar;
    while (len) {
        var randomNum = Math.random() * len-- | 0;
        thatChar = that[len], that[len] = that[randomNum], that[randomNum] = thatChar;
    }
    document.getElementById("moniker").textContent = that.join("");
}

window.addEventListener('click',
    function scrambler(str) {
        var thingy = str.textContent;
        var that = thingy.split("");
        var len = that.length;
        var thatChar;
        while (len) {
            var randomNum = Math.random() * len-- | 0;
            thatChar = that[len], that[len] = that[randomNum], that[randomNum] = thatChar;
        }
        document.getElementById("moniker").textContent = that.join("");
    }
);

use event listener