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javascriptgoogle-apps-script

Google Apps Scripting variables and values

When declaring a variable in a Google Apps script, when would I use let vs. const vs var, as in the following?

let sheet = range.getSheet();
const sheet = range.getSheet():
var sheet = range.getSheet();

Different tutorials use different terms. Are they interchangeable? I'd like to choose correctly.

Next, when should one use get.Value() vs get.Values()? I thought one was for a single value and the other for an array of values, but was I thrown an error when reading an email address using get.Value(). The error was: Error sending email to function () { [native code] }. The code worked when I changed it to get.Values().

Solution

  • Difference between getValue and getValues

    Though the condition on using both is the same, they are expecting different parameters to receive. getValue gets a value of a cell, while the getValues gets 2D array.

    Sample Code:

    function myFunction() {
  var ss = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  var range = ss.getRange("A1:A5").getValues();
  var range2 = ss.getRange("A1:A5").getValue();
  console.log("getValues: " + range)
  console.log("getValue: " + range2)
}

    In the sample code above, the line that uses get values will return all values of the range while the line that uses get value will return only the top left value of the range though the range contains lots of values

    Sample Output

    Sample output

    Data type that getValue() and getValues() handle

    getValue() and getValues() also differs from the type that they get, getValue() gets a single type value(string, number) while getValues() handles object types see the output of typeof() method below(which return the type of the parameter given)

    Sample Code

    function myFunction() {
  var ss = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  var range = ss.getRange("A1").getValues();
  var range2 = ss.getRange("A1:A5").getValue();
  console.log("getValues: " + typeof(range))
  console.log("getValue: " + typeof(range2))
}

    Sample output

    Output of typeof() method

    In your case, you might be encountering issue when using getValue due to the structure of the field where the email address is located, most likely, the data you're accessing (the email address) is part of a range or an item that is being returned as an array (even if it contains only one element)

    Difference of let, var and const

    In Google Apps Script, which is based on JavaScript, you have three main ways to declare variables: let, const, and var. Each has its own use case and behavior.

    1. let:

      • Scope: Block-scoped (Variable declared using let is only accessible within the block it is defined in).
      • Reassignment: Variables declared with let can be reassigned.

    2. const:

      • Scope: Also Block-scoped (like let).
      • Reassignment: Variables declared with const cannot be reassigned.

    3. var:

      • Scope: Function-scoped (i.e., the variable is accessible throughout the function in which it is defined).
      • Reassignment: Variables declared with var can be reassigned.

    When you require a variable that can be changed later, use let. For values that shouldn't be changed, use const. In current JavaScript, avoid using var because of its scope-related peculiarities.

    You can also check this post for more information: var, let and const as explained by Stackoverflow community

    Reference: Var, Let, and Const – What's the Difference? getValue()