/**
 * Created by Wizzer on 14-8-28.
 */
var num = 0;
var login = {
    initialize: function () {
        this.bindEvents();
    },
    bindEvents: function () {
        document.addEventListener('backbutton', this.eventBackButton, false);
    },
    eventBackButton: function () {
        num++;
        if (num > 1) {
            navigator.app.exitApp();
        }
        navigator.toast.show("再点击一次退出");
        // 3秒后重新计数
        var intervalID = window.setInterval(function() {
            num=0;
            window.clearInterval(intervalID);
        }, 3000);
    }
};

浮动提示插件见：
/?p=3026