send2slack.js

	if (updateFileMap.length != 0) {
		var slackApp = SlackApp.create(slackAccessToken);
		if(updateFileMap.length <= 20){
			var attachments = [];
			for( key in updateFileMap ){
			var item = updateFileMap[key];
			var title = item.updateType + "："+item.filename;
			var title_url = item.url;
			var text = item.lastUpdate?item.updateType+'日時：' + Utilities.formatDate(item.lastUpdate, "JST", "yyyy-MM-dd HH:mm:ss") + '\n':''
			var color = item.color;
			attachments.push({color:color, title:title, title_link:title_url, text:text});
			}
			
			slackApp.postMessage(drivelogId, '', {'icon_url':'https://upload.wikimedia.org/wikipedia/commons/d/da/Google_Drive_logo.png','username':'UpdateNotifier', 'attachments': JSON.stringify(attachments)});
		}else{
			var l = {};
			for( key in updateFileMap ){
				var item = updateFileMap[key];
				if(item.updateType in l){
					l[item.updateType].push(item.filename);
				}else{
					l[item.updateType] = [item.filename];
				}
			}
			for(key in l){
				var text = l[key].join("\n");
				var comment = l[key].length+"件のファイルが"+key+"されました。";
				console.log(comment, text);
				uploadTextFileToSlack(text, comment, drivelogId);

			}
		}
	}

uploadTextFileToSlack.js

function uploadTextFileToSlack(content, comment, channels){
	return UrlFetchApp.fetch("https://slack.com/api/files.upload", {method: "post", payload:{"content":content, initial_comment:comment,channels:channels}, headers:{"Authorization": "Bearer "+properties.getProperty('slackAccessToken2')}});
	Logger.log(res);
}