index.js

var instances = [],
    matchers = [];
// Miliseconds
matchers.push(/^[0-9]*$/.source);
// Month/Day/Year [hours:minutes:seconds]
matchers.push(/([0-9]{1,2}\/){2}[0-9]{4}( [0-9]{1,2}(:[0-9]{2}){2})?/
    .source);
// Year/Day/Month [hours:minutes:seconds] and
// Year-Day-Month [hours:minutes:seconds]
matchers.push(/[0-9]{4}([\/\-][0-9]{1,2}){2}( [0-9]{1,2}(:[0-9]{2}){2})?/
    .source);
// Cast the matchers to a regular expression object
matchers = new RegExp(matchers.join('|'));
// Parse a Date formatted has String to a native object

function parseDateString(dateString) {
    // Pass through when a native object is sent
    if (dateString instanceof Date) {
        return dateString;
    }
    // Caste string to date object
    if (String(dateString).match(matchers)) {
        // If looks like a milisecond value cast to number before
        // final casting (Thanks to @msigley)
        if (String(dateString).match(/^[0-9]*$/)) {
            dateString = Number(dateString);
        }
        // Replace dashes to slashes
        if (String(dateString).match(/\-/)) {
            dateString = String(dateString).replace(/\-/g, '/');
        }
        return new Date(dateString);
    } else {
        throw new Error('Couldn\'t cast `' + dateString +
            '` to a date object.');
    }
}
// Map to convert from a directive to offset object property
var DIRECTIVE_KEY_MAP = {
    'Y': 'years',
    'm': 'months',
    'w': 'weeks',
    'D': 'days',
    'H': 'hours',
    'M': 'minutes',
    'S': 'seconds',
};
// Returns an escaped regexp from the string

function escapedRegExp(str) {
    var sanitize = str.toString().replace(/([.?*+^$[\]\\(){}|-])/g, '\\$1');
    return new RegExp(sanitize);
}
// Time string formatter

function strftime(offsetObject) {
    return function(format) {
        var directives = format.match(/%(-|!)?[A-Z]{1}(:[^;]+;)?/gi);
        if (directives) {
            for (var i = 0, len = directives.length; i < len; ++i) {
                var directive = directives[i]
                    .match(/%(-|!)?([a-zA-Z]{1})(:[^;]+;)?/),
                    regexp = escapedRegExp(directive[0]),
                    modifier = directive[1] || '',
                    plural = directive[3] || '',
                    value = null;
                // Get the key
                directive = directive[2];
                // Swap shot-versions directives
                if (DIRECTIVE_KEY_MAP.hasOwnProperty(directive)) {
                    value = DIRECTIVE_KEY_MAP[directive];
                    value = Number(offsetObject[value]);
                }
                if (value !== null) {
                    // Pluralize
                    if (modifier === '!') {
                        value = pluralize(plural, value);
                    }
                    // Add zero-padding
                    if (modifier === '') {
                        if (value < 10) {
                            value = '0' + value.toString();
                        }
                    }
                    // Replace the directive
                    format = format.replace(regexp, value.toString());
                }
            }
        }
        format = format.replace('%_M1',offsetObject.minutes_1)
                        .replace('%_M2',offsetObject.minutes_2)
                        .replace('%_S1',offsetObject.seconds_1)
                        .replace('%_S2',offsetObject.seconds_2)
                        .replace('%_H1',offsetObject.hours_1)
                        .replace('%_H2',offsetObject.hours_2)
                        .replace('%_D1',offsetObject.days_1)
                        .replace('%_D2',offsetObject.days_2);
        format = format.replace(/%%/, '%');
        return format;
    };
}
// Pluralize

function pluralize(format, count) {
    var plural = 's',
        singular = '';
    if (format) {
        format = format.replace(/(:|;|\s)/gi, '').split(/\,/);
        if (format.length === 1) {
            plural = format[0];
        } else {
            singular = format[0];
            plural = format[1];
        }
    }
    if (Math.abs(count) === 1) {
        return singular;
    } else {
        return plural;
    }
}

function splitNumber (number){
    number = number+'';
    number = (number.length===1?('0'+number):number)+'';
    return number.split('');
}

// The Final Countdown
var Countdown = function(finalDate, option) {
    option = option || {};
    this.PRECISION = option.precision || 100; // 0.1 seconds, used to update the DOM
    this.interval = null;
    this.offset = {};
    // Register this instance
    this.instanceNumber = instances.length;
    instances.push(this);
    // Set the final date and start
    this.setFinalDate(finalDate);
};
var Eventor = require('eventor');
Eventor.mixTo(Countdown);
var pro = Countdown.prototype;

var fns = {
    start: function() {
        if (this.interval !== null) {
            clearInterval(this.interval);
        }
        var self = this;
        this.update();
        this.interval = setInterval(function() {
            self.update.call(self);
        }, this.PRECISION);
        return this;
    },
    stop: function() {
        clearInterval(this.interval);
        this.interval = null;
        this._dispatchEvent('stoped');
        return this;
    },
    toggle: function() {
        if (this.interval) {
            this.stop();
        } else {
            this.start();
        }
        return this;
    },
    pause: function() {
        return this.stop();
    },
    resume: function() {
        return this.start();
    },
    remove: function() {
        this.stop.call(this);
        instances[this.instanceNumber] = null;
    },
    setFinalDate: function(value) {
        this.finalDate = parseDateString(value); // Cast the given date
        return this;
    },
    getOffset: function(){
        this.totalSecsLeft = this.finalDate.getTime() - new Date().getTime(); // In miliseconds
        this.totalSecsLeft = Math.ceil(this.totalSecsLeft / 1000);
        this.totalSecsLeft = this.totalSecsLeft < 0 ? 0 : this.totalSecsLeft;
        // Calculate the offsets
        return {
            seconds: this.totalSecsLeft % 60,
            minutes: Math.floor(this.totalSecsLeft / 60) % 60,
            hours: Math.floor(this.totalSecsLeft / 60 / 60) % 24,
            days: Math.floor(this.totalSecsLeft / 60 / 60 / 24),
            weeks: Math.floor(this.totalSecsLeft / 60 / 60 / 24 / 7),
            months: Math.floor(this.totalSecsLeft / 60 / 60 / 24 / 30),
            years: Math.floor(this.totalSecsLeft / 60 / 60 / 24 / 365)
        };
    },
    update: function() {
        // Calculate the offsets
        this.offset = this.getOffset();
        // split offset only for days, hours, minutes, seconds and two number like 45, do not support 100

        var list = ['days','hours','minutes','seconds'];

        for(var i=0;i<list.length;i++){
            var key = list[i];
            var numbers = splitNumber(this.offset[key]);
            this.offset[key+'_1'] = numbers[0];
            this.offset[key+'_2'] = numbers[1];
        }
        // Dispatch an event
        if (this.totalSecsLeft === 0) {
            this.stop();
            this._dispatchEvent('finish');
        } else {
            this._dispatchEvent('update');
        }
        return this;
    },
    _dispatchEvent: function(eventName) {
        var event = {};
        event.finalDate = this.finalDate;
        event.offset = this.offset;
        event.strftime = strftime(this.offset);
        this.emit(eventName, event);
        this.emit('tick',event);
    }
}

for (var i in fns) {
    pro[i] = fns[i];
}

module.exports = Countdown;