Gatsby: spread operator with Set not working?

[kuworking]

I am testing a very simple code

  let hol = new Set(['me','you','others'])
  console.log(hol)
  let hol2 = [...hol]
  console.log(hol2[1]) // should give 'you'

and this works as intended in for example in https://codepen.io/kuworking/pen/mZEWgV

But I'm trying this in a gatsbyjs webpage of mine, and I am not getting this, instead hol2 is not an array but a set within an array (seen in Chrome console)

[Set(3)]
0: Set(3)
size: (...)
__proto__: Set
[[Entries]]: Array(3)
0: "me"
1: "you"
2: "others"
length: 3
length: 1
__proto__: Array(0)

Why is this happening?

  gatsby 2.3.31
  System:
    OS: Windows 10
    CPU: (4) x64 Intel(R) Core(TM) i5-6600K CPU @ 3.50GHz
  Binaries:
    Yarn: 1.15.2 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
    npm: 6.4.1 - C:\Program Files\nodejs\npm.CMD

[superhawk610]

Hey @kuworking, in order to diagnose your issue, it would be super helpful to have a copy of your project's source code. If you haven't already, upload your project to a GitHub repo and post a link to it below. If you need help, check out this article on posting a reproducible test case.

Once you post your example, it would also be helpful to post the file/line number where your issue is occurring.

[circlingthesun]

@superhawk610 I've reproduced it here: https://github.com/circlingthesun/gatsby-set-bug

[circlingthesun]

It looks like the issue is caused by the default babel config having "loose" set to false on "@babel/preset-env".

[circlingthesun]

You can work around this by adding the following to your gatsby-node.js:

exports.onCreateBabelConfig = ({ actions, stage }) => {
  actions.setBabelPlugin({
    name: `@babel/plugin-transform-spread`,
    options: {
      loose: false,
    },
  });
};

[kuworking]

You can work around this by adding the following to your gatsby-node.js:

exports.onCreateBabelConfig = ({ actions, stage }) => {
  actions.setBabelPlugin({
    name: `@babel/plugin-transform-spread`,
    options: {
      loose: false,
    },
  });
};

It does work for me, thanks! :)
*I assume this won't be necessary once this issue is automatically closed and gatsby is updated

[wardpeet]

Fixed in [email protected]