Additional support for parsing multiple periods in one string and adding them up (eg. "10h 30m")

period.js

function getPeriods(periods) {  
    var splittedPeriods = periods.match(/\d+(ms|s|m|h|d|o|y)/g);
    var sum = 0;
    
    splittedPeriods.forEach(function(period) {
        sum += getPeriod(period);
    });
    
    return sum;
};

function getPeriod(period) {
    var number, letter, letters, time;

    if (typeof period !== "string") {
        throw new Error("sorry, only string is correct, not " + typeof period);
    }

    /**
     * Parse number from period.
     * @type {number}
     */
    number = parseInt(period, 10);

    /**
     * Parse letters from period.
     * @type {Array}
     */
    letters = period.match(/[a-z]/mig);

    if (letters === null) {
        throw new Error("give me some letters in \"" + period + "\"");
    }

    /**
     * Cast *Array* to lower case *string*.
     * @type {string}
     */
    letter = letters.join("").toLowerCase();

    /**
     * Start build time from number.
     * @type {number}
     */
    time = number;

    /**
     * Transform time to concrete period.
     */
    switch (letter) {
        case "ms": break;
        case "s": time *= 1000; break;
        case "m": time *= 1000 * 60; break;
        case "h": time *= 1000 * 60 * 60; break;
        case "d": time *= 1000 * 60 * 60 * 24; break;
        case "o": time *= 1000 * 60 * 60 * 24 * 30; break; // month is 30 days
        case "y": time *= 1000 * 60 * 60 * 24 * 365; break; // year is 365 days
    }

    return time;
};

/**
 * TEST DATA
 */
["10ms", "3s", "5m", "1h", "7d", "1o", "3y"].forEach(function (period) {
    console.log(getPeriod(period));
});