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google.script.run.withSuccessHandler() returns Undefined

I created an array in a separate GS file using the code provided below. I tried calling it in my HTML file. My goal is to compare the contents the array to the parameter email. However, the value returned by google.script.run.withSuccessHandler() is undefined

//in GS
function mailGetter()
{
  //open sheet
  var sheet = SpreadsheetApp.openByUrl("https://sheet.url").getSheetByName("Email Sheet").activate();
  //get size of given row range
  var row_data_email = sheet.getRange("C2:C").getValues();
  var emailArray = row_data_email.join().split(',').filter(Boolean);
  Logger.log(emailArray);
  
  return emailArray;
}
//in HTML
function checkEmail(email) 
    {
      var reg1 = /^[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,4}$/;
      var arraySize = google.script.run.withSuccessHandler(misc).sizeGetter(); 
      console.log(arraySize);
      var emailArray = new Array(arraySize);
      emailArray = google.script.run.withSuccessHandler(misc).mailGetter();
      console.log(emailArray);
      
      if (reg1.test(email) == false) 
      {
        emails.style.border = "1px solid red";
        document.getElementById('submitBtn').disabled = true;
      } 
      else if (reg1.test(email) == true) 
      {
        emails.style.border = "1px solid green";
        document.getElementById('submitBtn').disabled = false;
      }
      
      for (var row = 0; row < arraySize; row++)
      {
        if (emailArray[row][0] == email)
        {
          emails.style.border = "1px solid green";
          document.getElementById('submitBtn').disabled = false;
          break;
        }
        else if (emailArray[row][0] != email)
        {
          emails.style.border = "1px solid red";
          document.getElementById('submitBtn').disabled = true;
        }
      }
    }

    function misc()
    {
      console.log("Pass");
    }
like image 642
coding_is_hard Avatar asked Sep 03 '25 15:09

coding_is_hard


1 Answers

Issue:

  • Using a asynchronous function's(google.script.run) return value, which will always be undefined.

Solution:

  • Use successHandler as mentioned in another answer or We can use promises with async/await.

Snippet:

/*Create a promise around old callback api*/
const p = func => 
  new Promise(resolve=>
    google.script.run.withSuccessHandler(resolve)[func]()
  );

async function checkEmail(email) //modified
    {
      var arraySize = await p('sizeGetter');//Wait to resolve
      console.log(arraySize);
      //var emailArray = new Array(arraySize);
      var emailArray = await p('mailGetter');//Wait to resolve
      console.log(emailArray);
      //....
    }

Note:

  • It's better to reduce the number of calls to the server. If you can combine both Getters to a single server function, it'll be better.
  • The above is a snippet showing how to use async/await. But if you wait for each response from the server as shown above, your front end/UI will be slow. Wait only if absolutely necessary. Calls to server should be non-blocking/asynchronous.

References:

  • Promises
  • async
  • await
like image 87
TheMaster Avatar answered Sep 05 '25 11:09

TheMaster