function doPost(e) {
var my_token = "slack token";
var postData = JSON.parse(e.postData.getDataAsString());

if(postData.type == 'url_verification') {
var res = {'challenge':postData.challenge}
return ContentService.createTextOutput
(JSON.stringify(res)).setMimeType(ContentService.MimeType.JSON);
}
else{
if(my_token == postData.token) {
cache = CacheService.getScriptCache();
var data = cache.get(postData.event.event_id);
if(data==null){
cache.put
(postData.event.event_id,postData.event.event_id,60);

UrlFetchApp.fetch(
' https://your address.ngrok.io/google-home-notifier', {
'method': 'POST',
'contentType': 'application/x-www-form-urlencoded',
'payload': {'text' : text}
}
);
}
}
var res="";
return ContentService.createTextOutput
(JSON.stringify(res)).setMimeType(ContentService.MimeType.JSON);
}
}

var language = 'en'; // default language code
if(ja2Bit(text)) {
language = 'ja';
}
..
..
..
function ja2Bit ( str ) {
return ( str.match(/^[\u30a0-\u30ff\u3040-\u309f\u3005-\u3006\u30e0-\u9fcf]+$/) )? true : false;
}