How can I pass an Apps Script function value to another function and have it invoked there?

Question

Thanks to this answer, I've been able to invoke generic functions with any number of parameters. But as I was further refining my code, I came across this problem:

function test() {
  var object = {to: "[email protected]", subject: "subject line", body: "using object"};
  var attributes = ["[email protected]", "subject line", "using attributes"];
  pass_to_func1(MailApp.sendEmail, attributes); 
  pass_to_func2(MailApp.sendEmail, object);
}

function pass_to_func1(func, attributes) {
  try {
    func.apply(null, attributes);
  }
  catch (e) {
    Logger.log(e.name + ": " + e.message);
    return;
  }
  Logger.log("pass_to_func1 success");
}

function pass_to_func2(func, object) {
  try {
    func.call(null, object);
  }
  catch (e) {
    Logger.log(e.name + ": " + e.message);
    return;
  }
  Logger.log("pass_to_func2 success");
}

As you can see, I am trying to pass the MailApp.sendEmail funtion value as an argument to a "middle-man" function, of which I have two versions.

One invokes the function parameter with Function.prototype.apply with an array of strings as its argument (send-to email, subject, body).

The other invokes the function parameter with Function.prototype.call with a javascript object as its argument (see the MailApp developer reference for more info).

Both of them throw the same error, shown below:

InternalError: Method "sendEmail" was invoked with [object Object] as "this" value that can not be converted to type MailApp.

I don't know how to make sense of an error like that and I would appreciate any help.

Look up Function::call and Function::apply in MDN's javascript reference. You probably haven't 'scoped' the function call to the right object (which I suspect should be MailApp in this case) — TheAddonDepot
I actually just figured this out as well! Thank you for helping anyway, you were right on — Manuel

Manuel Manuel · Accepted Answer · 2018-02-12T18:25:29

So I just figured out what the problem is.

I needed to replace

func.apply(null, attributes); and func.call(null, object);

with

func.apply(MailApp, attributes);

and func.call(MailApp.object);

How can I pass an Apps Script function value to another function and have it invoked there?

1 Answers