empty

/**
 * Determine if v is empty. where empty is: null, false, zero, a blank string, 
 * Object with no keys, Array with 0 length, Set or Map with 0 size
 * Note:  weakMap & weakSet can't be determined if they are empty.
 *
 * @param v
 * @returns {boolean}
 */
function empty(v) {
    if(typeof v === 'undefined' || null === v)
        return true;
    if(Array.isArray(v))
        return v.length === 0;
    if(typeof v === 'object') {
        if(v instanceof Set || v instanceof Map)
            return v.size === 0;
        return Object.keys(v).length === 0;
    }
    if('' == v)
        return true;
    if(typeof v === 'function')
        return false;
    return !isNaN(v) && parseFloat(v) === 0.00;
}