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qr-js

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qr.js is a pure JavaScript library for QR code generation using canvas.

Install

Install using the package manager for your desired environment(s):

# for node.js:
$ npm install qr-js
# OR; for the browser:
$ bower install qr-js

Examples

In the browser:

<html>
  <body>
    <canvas id="qr-code"></canvas>
    <script src="/path/to/qr.min.js"></script> 
    <script>
      qr.canvas({
        canvas: document.getElementById('qr-code'),
        value: 'http://neocotic.com/qr.js'
      });
    </script> 
  </body>
</html>

In node.js:

var qr = require('qr-js');
 
qr.saveSync('http://neocotic.com/qr.js', 'qrcode.png');

API

Standard Data

The following configuration data options are recognised by all of the core API methods (all of which are optional):

Property Description Default
background Background colour to be used #fff
canvas <canvas> element in which the QR code should be rendered Creates a new element
foreground Foreground colour to be used #000
level ECC (error correction capacity) level to be applied L
size Module size of the generated QR code 4
value Value to be encoded in the generated QR code ""

canvas([data|value])

Renders a QR code in an HTML5 <canvas> element for a given value.

// Render the QR code on a newly created canvas element 
var canvas = qr.canvas('http://neocotic.com/qr.js');
// Re-render the QR code on an existing element 
qr.canvas({
  canvas: canvas,
  value: 'https://github.com/neocotic/qr.js'
});

image([data|value])

Renders a QR code in an HTML <img> element for a given value.

// Render the QR code on a newly created img element 
var img = qr.image('http://neocotic.com/qr.js');
// Re-render the QR code on an existing element 
qr.image({
  image: img,
  value: 'https://github.com/neocotic/qr.js'
});

Additional Data

As well as the Standard Data, this method also accepts the following additional data options:

Property Description Default
image <img> element in which the QR code should be rendered Creates a new element
mime MIME type to process the QR code image image/png

save([data|value][, path], callback)

Saves a QR code, which has been rendered for a given value, to the user's file system.

// Render a QR code to a PNG file 
qr.save('http://neocotic.com/qr.js', 'qr.png', function(err) {
  if (err) throw err;
 
  // ... 
});
// Render a QR code to a JPEG file 
qr.save({
  mime: 'image/jpeg',
  path: 'qr.jpg',
  value: 'https://github.com/neocotic/qr.js'
}, function(err) {
  if (err) throw err;
 
  // ... 
});

Note: Currently, in the browser, this just does it's best to force a download prompt. We will try to improve on this in the future.

Additional Data

As well as the Standard Data, this method also accepts the following additional data options:

Property Description Default
mime MIME type to process the QR code image image/png
path Path to which the QR code should be saved
Ignored in browsers
Required if not specified as an argument

saveSync([data|value][, path])

Synchronous save(3).

toDataURL([data|value])

Returns a data URL for rendered QR code. This is a convenient shorthand for dealing with the native HTMLCanvasElement.prototype.toDataURL function.

console.log(qr.toDataURL('http://neocotic.com/qr.js')); // "data:image/png;base64,iVBORw0KGgoAAAA..." 
console.log(qr.toDataURL({
  mime: 'image/jpeg',
  value: 'https://github.com/neocotic/qr.js'
})); // "data:image/jpeg;base64,/9j/4AAQSkZJRg..." 

Additional Data

As well as the Standard Data, this method also accepts the following additional data options:

Property Description Default
mime MIME type to process the QR code image image/png

Miscellaneous

noConflict()

Returns qr in a no-conflict state, reallocating the qr global variable name to its previous owner, where possible.

This is really just intended for use within a browser.

<script src="/path/to/conflict-lib.js"></script>
<script src="/path/to/qr.min.js"></script>
<script>
  var qrNC = qr.noConflict();
  // Conflicting lib works again and use qrNC for this library onwards... 
</script> 

VERSION

The current version of qr.

console.log(qr.VERSION); // "1.1.4" 

Canvas Support

For browser users; their browser must support the HTML5 canvas element or the API will throw an error immediately.

For node.js users; qr.js heavily depends on node-canvas to support the HTML5 canvas element in the node.js environment. Unfortunately, this library is dependant on Cairo, which is not managed by npm. Before you are able to install qr.js (and it's dependencies), you must have Cairo installed. Please see their wiki on steps on how to do this on various platforms:

https://github.com/LearnBoost/node-canvas/wiki/_pages

Bugs

If you have any problems with this library or would like to see the changes currently in development you can do so here;

https://github.com/neocotic/qr.js/issues

Questions?

Take a look at docs/qr.html to get a better understanding of what the code is doing.

If that doesn't help, feel free to follow me on Twitter, @neocotic.

However, if you want more information or examples of using this library please visit the project's homepage;

http://neocotic.com/qr.js