Creating a QR-code containing a link in NodejS - html

Question

I'm working on a project right now, i need to create a qrcode that contains a specific information in NodeJS. I have started by creating the canvas in HTML, and take it in NodeJS
<canvas id="canvas" width="300" height="300"></canvas>
And then in my NodeJS file, i'm launching my function
const fs = require('fs');
const qrcode = require('qrcode');
module.exports = {
generateQr: function(link){
var canvas = new qrcode(document.getElementById('canvas'));
qrcode.toCanvas(canvas, link, function (error) {
if (error) console.error(error)
console.log('success!');
});
}
};
Unfortunately, i got the error :
ReferenceError: document is not defined
From the above code, does it look correct ? Does the Qrcode get the data i'm passing, and then what should i do so the QR-code appear in my HTML ?
Thank you for your help

Answer 1

document is a browser-specific global object, you can't access it in node
In node environment, you could generate an image with QR code and use it.
Example:
Async/Await style:
const fs = require('fs');
const qrcode = require('qrcode');
module.exports = {
generateQr: async link => {
const qrCodeDataUrl = await qrcode.toDataURL(link);
// ...
}
};
Promise style:
const fs = require('fs');
const qrcode = require('qrcode');
module.exports = {
generateQr: link => {
qrcode.toDataURL(link)
.then(data => {
const qrCodeDataUrl = data;
// ...
})
.catch(err => {
console.error(error);
// ...
});
}
};
Callback style:
const fs = require('fs');
const qrcode = require('qrcode');
module.exports = {
generateQr: link => {
qrcode.toDataURL(link, function(err, data) {
if (error) console.error(error);
const qrCodeDataUrl = data;
// ...
});
}
};
To render it in an HTML-file you could use template-engine of your choice:
Example with ejs:
const ejs = require('ejs');
// In some route
const qrCodeDataUrl = await generateQr('some link');
const html = ejs.render('<img src="<%= qrCodeDataUrl %>" />', {qrCodeDataUrl});
res.header('Content-Type', 'text/html');
res.send(html);
// ...
Note: It's a simplified example. Please check ejs docs for more details