s-ike

var USER_ID = 'xxxxxxx';

var MAIL_TO = 'xxxxxxx@xxxxxxx';
var MAIL_FROM = 'xxxxxxx@xxxxxxx';
var MAIL_FROMNAME = 'mail sender name';
var MAIL_BCC = 'xxxxxxx@xxxxxxx';
var MAIL_SUBJECT = 'mail subject';

function doPost(e) {
  var json = JSON.parse(e.postData.contents);

s-ike

// Getting current device language and checking whether it is Japanese（日本語かどうか）
+ (BOOL)isLocaleJapanese {
    NSArray *languages = [NSLocale preferredLanguages];
    NSString *languageID = [[languages objectAtIndex:0] substringToIndex:2];
    
    if ([languageID isEqualToString:@"ja"]) {
        return YES;
    }
    return NO;
}