Form handler that doesn't work in Firefox

Catching clicks

formEvent: function (event) {

	    console.log(event);              // "Not defined!" -- Firefox
            eventType = event.target.type;

            switch (eventType) {
                case "checkbox":
                    classArray = event.target.classList;
                    key = classArray[0];
                    value = classArray[1];
                    checkedStatus = event.target.checked;
                    this.toggleShown(key, value, checkedStatus, "checkbox");
                    break;
                case "radio":
                    this.sortThingsByColumn(event.target.className);
                    return this;
                    break;
                case "select-one":
                    value = event.target.value;
                    key = event.target.classList[0];
                    this.toggleSelect(key, value);
                    break;
                default:
                    break;
            }
        },