10进制与62进制相互转换

/**
 * @file: 10进制与62进制相互转换
 * @author 沈萬三
 * @date: 2015-09-15
 */
define(function() {
    var syshift = {};
    // 防止重复出现相同ID;
    var temp = -100000;
    var chars = '0123456789abcdefghigklmnopqrstuvwxyzABCDEFGHIGKLMNOPQRSTUVWXYZ';
    /**
     * 10进制转换为62进制
     * @param {number} num 形参10进制数字
     *  @return {string} 返回值是一个时间毫秒数转换的62进制字符串
     */
    syshift.sys10to62 = function(num) {
        var charsSrr = chars.split('');
        var radix = chars.length;
        var qutient = +num;
        var arr = [];
        do {
            mod = qutient % radix;
            qutient = (qutient - mod) / radix;
            arr.unshift(chars[mod]);
        } while (qutient);
        return arr.join('');
    };

    /**
     * 62进制转换为10进制
     * @param {Object} number_code 形参62进制数字
     * @return {number} 返回值是一个62进制字符串转换的数字
     */
    syshift.sys62to10 = function(numberCode) {
        var radix = chars.length;
        var numberCode = String(numberCode);
        var len = numberCode.length;
        var i = 0;
        var originNumber = 0;
        while (i < len) {
            originNumber
                += Math.pow(radix, i++) * chars.indexOf(numberCode.charAt(len - i) || 0);
        }
        return originNumber;
    };

    /**
     * 利用当前时间产生不同的ID
     *  @return {string} 返回值是一个时间毫秒数转换的62进制字符串
     */
    syshift.getIdFromDate = function() {
        var theDate = parseInt(new Date().getTime(), 10);
        if (theDate === temp) {
            theDate++;
        }
        else {
            temp = theDate;
        }
        return this.sys10to62(theDate);
    };

    return syshift;
});