Unable to return an object from the javascript

[ferozed]

terraform {
  required_providers {
    javascript = {
      source = "apparentlymart/javascript"

      # Until this provider has a stable release, always select an exact
      # version to avoid adopting new releases that may have breaking changes.
      version = "0.0.1"
    }
  }
}


data "javascript" "example" {
  source = <<-EOT
  { x: "1", y: "2" }
  EOT

  vars = {
  }
}

output "raw_schema" {
	value = data.javascript.example.result
}

output "validated_schema" {
	value = data.javascript.example.result
}

Returns plan error:

│ Error: JavaScript Syntax Error
│
│   with data.javascript.example,
│   on main.tf line 38, in data "javascript" "example":
│   38:   source = <<-EOT
│   39:   { x: "1", y: "2" }
│   40:   EOT
│
│ SyntaxError: (anonymous): Line 1:12 Unexpected token :

Any ideas what I am doing wrong?

However, if I just return one value in the object

{  x: "1" }

I get

Changes to Outputs:
  + raw_schema       = "1"
  + validated_schema = "1"

Arrays are returned correctly. Just not objects.

Removing the comma causes it to succeed plan, but return the last value in the object.

  source = <<-EOT
  { x: "1"
  y : "2" }
  EOT

returns:

  + raw_schema       = "2"
  + validated_schema = "2"

[apparentlymart]

Hi @ferozed!

I think what you've encountered here is an ambiguity in the JavaScript language: it uses braces { } for both lexical scopes and for object construction expressions.

I think the lexical scope meaning is taking precedence here, and so the JavaScript engine is trying to handle the contents of the braces as a sequence of statements rather than as a sequence of object properties. I've drawn that conclusion because:

• The first example was invalid, perhaps because the whole sequence x: "1", y: "2" is not a valid JavaScript statement.
• x: "1" I think is valid because it looks like x is serving as a label for the expression statement "1".
• Splitting it over multiple lines without a comma presumably activated automatic semicolon insertion, making x: "1" and y: "2" both appear as labelled statements in a similar way as the previous point. The result of a statement block is the result of its last expression statement, and so it returned "2". The statement block itself was the last statement in the overall program, so it returned "2" as well.

With all of this said, I believe the typical ways to resolve ambiguities like this in JavaScript are:

• Explicitly write return before the opening brace, making it clear to the parser that this brace is the start of an expression rather than the start of a statement.
• Put the braces in parentheses -- ({ to start and }) to end -- again to force the parser to treat what's inside as an expression rather than as a statement.

I think the return trick might not work here because at the top level of the program we're not in the context of a function and so I'm not sure if it's valid to say return in this context, but the second approach of placing it in parentheses should work.

Can you give that a try and let me know if that helps? If so, I'll plan to add a note to the documentation about it. Thanks!

[ferozed]

Hi!

Thanks for the detailed explanation.

I tried putting a return but that didnt work either.

I didnt try the parenthesis, but the following works:

  var out = {};
  out.x = "1";
  out.y = "2";
  out;