openrosa-xpath-evaluator/src/utils/date.js

Wrapper for browsers' XPath evaluator with added support for OpenRosa extensions.

const DATE_STRING =
    /^\d\d\d\d-\d{1,2}-\d{1,2}(?:T\d\d:\d\d:\d\d\.?\d?\d?(?:Z|[+-]\d\d:\d\d)|.*)?$/;

function dateToDays(d) {
    return d.getTime() / (1000 * 60 * 60 * 24);
}

function dateStringToDays(d) {
    let temp = null;
    if (d.indexOf('T') > 0) {
        temp = new Date(d);
    } else {
        temp = d.split('-');
        temp = new Date(temp[0], temp[1] - 1, temp[2]);
    }
    return dateToDays(temp);
}

/**
 * Get the number of days in any particular month
 * @link https://stackoverflow.com/a/1433119/1293256
 * @param  {integer} m The month (valid: 0-11)
 * @param  {integer} y The year
 * @return {integer}   The number of days in the month
 */
const daysInMonth = function (m, y) {
    switch (m) {
        case 1:
            return (y % 4 === 0 && y % 100) || y % 400 === 0 ? 29 : 28;
        case 8:
        case 3:
        case 5:
        case 10:
            return 30;
        default:
            return 31;
    }
};

/**
 * Check if a date is valid
 * @link https://stackoverflow.com/a/1433119/1293256
 * @param  {[type]}  y The year
 * @param  {[type]}  m The month
 * @param  {[type]}  d The day
 * @return {Boolean}   Returns true if valid
 */
const isValidDate = function (y, m, d) {
    m = parseInt(m, 10) - 1;
    return m >= 0 && m < 12 && d > 0 && d <= daysInMonth(m, y);
};

module.exports = {
    DATE_STRING,
    dateToDays,
    dateStringToDays,
    isValidDate,
};