required module in node.js is always undefined

user_3902947 0
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Currently experiencing something that is absolutely baffling. I am requiring the 'qrcode' module which I installed via npm (npm --save install qrcode).

const {
    QRCode
} = require('qrcode');

The module is listed in my package.json and does exist in node_modules. However, this is absolutely always 'undefined'. When hovering over the string in the require statement I see that it is some how referencing a node_modules directory in my local/AppData directory which I'm assuming is the global directory for modules. Using this path always results in 'undefined'. I then tried switching the path to reference the local node_modules qrcode and still 'undefined'. I've read everything here https://www.npmjs.com/package/qrcode but doesn't help with the issue I'm seeing and there appears to be not a single conversation on google about this.

TypeError: Cannot read property 'toDataURL' of undefined

When using the 'qrcode' string it is using something in the @types folder which I thought was for ES6 which I am not using. No idea how to proceed nothing adds up here, any help greatly appreciated!

Node.js example from npm package page(if only it were this easy)

var QRCode = require('qrcode')
 
QRCode.toDataURL('I am a pony!', function (err, url) {
  console.log(url)
})
es6-modules node-modules node.js qr-code
1 Answers

When you do this:

const {
    QRCode
} = require('qrcode');

You are expecting a QRCode property on the object that the module exports. This is called object destructing assignment in ES6. It is shorthand for and equivalent to this:

const QRCode = require('qrcode').QRCode;

And, since the object the module exports does NOT have a .QRCode property, you get nothing but undefined.

Instead, the top level object it exports is the QRCode object so you need to do this:

const QRCode = require('qrcode');

If you wanted a specific property that it was exporting, you could then do something like this:

const { toDataURL } = require('qrcode');
user_8166200
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