Typescript rendering array as [object Object] when using console.log

Question

I have an object in typescript "obj". When I run:

console.log(obj);

It renders as the following in the terminal console:

[object Object]

It's only after i wrap it in a JSON.stringify(obj) method that it renders the object as expected:

[{"allowed_values":["true"],"property":"pro1","required":"true"}]

What am I missing? Why is the object not being rendered as a JSON when I run "console.log()"?

Here is the scenario that captures the issue I am seeing:

violation = {"my_properties":[{"allowed_values":[{"Ref":"The bucket's logical resource name"}],"property":"BucketPolicy.Properties.Bucket","required":"true"}],"decision":"deny","message":"Some message.","policy_id":"FT_S3_0004","resource":"MyFirstBucketB8884501","type":"AWS::S3::Bucket","controls":["NIST-800-53-SA-8(2)"]}
console.log(violation)

This outputs:

{
  my_properties: [
    {
      allowed_values: [Array],
      property: 'BucketPolicy.Properties.Bucket',
      required: 'true'
    }
  ],
  decision: 'deny',
  message: 'Some message.',
  policy_id: 'FT_S3_0004',
  resource: 'MyFirstBucketB8884501',
  type: 'AWS::S3::Bucket',
  controls: [ 'NIST-800-53-SA-8(2)' ]
}

(notice that it prints [Array] rather than the actual elements in the array).

@Darth.Vader Make sure you're not concatenating a string with your `obj`. Also, if you import `util` using `const util = require("util");` what does `console.log(obj[util.inspect.custom])` show? — Nick Parsons, Jul 22 '21 at 23:37
The code you've posted doesn't do what you claim it does. Post a complete minimal example that demonstrates the problem and then we can help you find exactly what's wrong. — Alex Wayne, Jul 22 '21 at 23:44
@AlexWayne - I just posted a working example with the issue I am seeing. Please check my original question with an updated example.. — Darth.Vader, Jul 24 '21 at 21:22
Ah yes, node's console.log can abbreviate deeply nested values for brevity in the terminal. See https://stackoverflow.com/questions/10729276/how-can-i-get-the-full-object-in-node-jss-console-log-rather-than-object for solutions to that. — Alex Wayne, Jul 25 '21 at 01:15

score 1 · Answer 1 · answered Jul 22 '21 at 23:30

I think you aren't telling us the whole story. I can log the array object just fine using

console.log([{"allowed_values":["true"],"property":"pro1","required":"true"}]);

What you are seeing will happen, however, if you do something like this:

console.log("obj:" + obj);

In that case, .toString() is implicitly called in order to append the object to the preceding string. You can do this alternative and it will work:

console.log("obj:", obj);

score 0 · Answer 2 · answered Jul 22 '21 at 23:18

0

You can't convert an entire object to a string, and [object Object] is what the console.log outputs when it sees an object. Only if we convert it to a string then the logger will long the string representation of the object.

answered Jul 22 '21 at 23:18

Joseph Balnt

130
9

1

The console logs that actual object when it sees an object, not [object Object] -`console.log({x: 1});` shows `{x: 1}`, and not [object Object] – Nick Parsons Jul 22 '21 at 23:22

Typescript rendering array as [object Object] when using console.log

2 Answers2