toggle方法

var toggle = (function () {
    var a = true;
    return function (fn1, fn2) {
        a = !a;
        var toggler = function () {
            if (a) {
                return fn1;
            } else {
                return fn2;
            }
        };
        return this.onclick = toggler();
    }
})();

var div = document.getElementsByTagName("div")[0];
div.onclick = function () {
    toggle(function () {
        div.className = "red";
    }, function () {
        div.className = "orange";
    });
};