apps_email.js

function myFunction() {
  //https://developers.google.com/apps-script/reference/mail/mail-app#sendemailmessage
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheets()[0];
  var charts = sheet.getCharts()[0];
  var chart_image = charts.getAs("image/png").setName("hourly_chart")
  var d = new Date();
  var currentTime = d.toLocaleTimeString(); 
  
  
  Logger.log(chart_image);
  
  MailApp.sendEmail({
    to: "xxx",
    cc: "aaa, aaa, aaa, aaa",
    subject: "Hourly Report Draft: " + currentTime,
    htmlBody: "Hourly Data: <br> <img src='cid:chartImage'><br>",
    inlineImages:
    {
    chartImage: chart_image
  }
                    });
  
  
  // getrange --> getvalues returns a nested array of strings
  function flatten(data) {
    var flattened = data.reduce(function(a, b) {
      return a.concat(b);
    }, []).map(function(val) {
      return Math.round(parseFloat(val))
    });
    return flattened;
  }
  
  // Using Named Ranges
  var last_week = flatten(SpreadsheetApp.getActiveSpreadsheet().getRangeByName('lastweek').getValues());
  var last_year = flatten(SpreadsheetApp.getActiveSpreadsheet().getRangeByName('lastyear').getValues()); //.join(",\n")
  var today = flatten(SpreadsheetApp.getActiveSpreadsheet().getRangeByName('today').getValues());
  
  var yoy_diff = "Realtime YoY Report: \n YoY Difference: \n";
  
  for (var i = 0; i < 24; i++) {
    //Logger.log(today[i] - last_year[i]);
    var diff = today[i] - last_year[i];
    yoy_diff += "Hour: " + i + " $" + diff + "\n";
  }
  
  //Logger.log(yoy_diff);  
  
  
  // Slack Set-up stuff
  var url = "https://hooks.slack.com/services/xxxxx/xxx/xxxx";
  
  var payload = {
    "text": yoy_diff 
  }
  
  
  // Sent to slack 
  function sendToSlack_(url, payload) {
    var options = {
      "method": "post",
      "contentType": "application/json",
      "payload": JSON.stringify(payload)
    };
    
    return UrlFetchApp.fetch(url, options)
  }
  
  
  //  sendToSlack_(url, payload); // call func
  
  
}