Easthing-qrcode NPM

node-qrcode

QR code/2d barcode generator.

Highlights

Works on server and client
CLI utility
Save QR code as image
Support for Numeric, Alphanumeric, Kanji and Byte mode
Support for mixed modes
Support for chinese, cyrillic, greek and japanese characters
Support for multibyte characters (like emojis :smile:)
Auto generates optimized segments for best data compression and smallest QR Code size

Installation

Inside your project folder do:

npm install --save qrcode

or, install it globally to use qrcode from the command line to save qrcode images or generate ones you can view in your terminal.

npm install -g qrcode

Dependencies

node-canvas is required. (note: this dependency is only needed for server side use and will be likely removed in the future)

Install node-canvas dependencies

node-canvas is a native module and requires dev packages of Cairo and Pango to compile. Make sure to have these libs available on your system before run npm install qrcode

Installation instructions are available on node-canvas page.

Usage

CLI

qrcode <text> [output file]

Output image format is detected from file extension. Only png and svg format are supported for now.

If no output file is specified, the QR Code will be rendered directly in the terminal.

Example

qrcode "Draw a QR Code in my terminal"

qrcode "I like to save qrs as a PNG" qr.png

qrcode "I also like to save them as a SVG" qr.svg

Browser

node-qrcode can be used in browser through module bundlers like Browserify and Webpack or by including the precompiled bundle present in build/ folder.

Module bundlers

<!-- index.html -->
<html>
  <body>
    <canvas id="canvas"></canvas>
    <script src="bundle.js"></script>
  </body>
</html>

// index.js -> bundle.js
var QRCode = require('qrcode')
var QRCodeDraw = new QRCode.QRCodeDraw()
var canvas = document.getElementById('canvas')

QRCodeDraw.draw(canvas, 'sample text', function (error, canvas) {
  if (error) console.error(error)
  console.log('success!');
})

Precompiled bundle

<canvas id="canvas"></canvas>

<script src="/build/qrcode.min.js"></script>
<script>
  var qrcodedraw = new qrcodelib.qrcodedraw()

  qrcodedraw.draw(document.getElementById('canvas'), 'sample text', function (error, canvas) {
    if (error) console.error(error)
    console.log('success!');
  })
</script>

Precompiled files are generated in build/ folder during installation. To manually rebuild the lib run:

npm run build

NodeJS

Simply require the module qrcode

var QRCode = require('qrcode')

QRCode.toDataURL('I am a pony!', function (err, url) {
  console.log(url)
})

Error correction level

Error correction capability allows to successfully scan a QR Code even if the symbol is dirty or damaged. Four levels are available to choose according to the operating environment.

Higher levels offer a better error resistance but reduce the symbol's capacity. If the chances that the QR Code symbol may be corrupted are low (for example if it is showed through a monitor) is possible to safely use a low error level such as Low or Medium.

Possible levels are shown below:

Level	Error resistance
L (Low)	~7%
M (Medium)	~15%
Q (Quartile)	~25%
H (High)	~30%

The percentage indicates the maximum amount of damaged surface after which the symbol becomes unreadable.

Error level can be set through options.errorCorrectionLevel property. If not specified, the default value is M.

QRCode.toDataURL('some text', { errorCorrectionLevel: 'H' }, function (err, url) {
  console.log(url)
})

QR Code capacity

Capacity depends on symbol version and error correction level. Also encoding modes may influence the amount of storable data.

The QR Code versions range from version 1 to version 40. Each version has a different number of modules (black and white dots), which define the symbol's size. For version 1 they are 21x21, for version 2 25x25 e so on. Higher is the version, more are the storable data, and of course bigger will be the QR Code symbol.

The table below shows the maximum number of storable characters in each encoding mode and for each error correction level.

Mode	L	M	Q	H
Numeric	7089	5596	3993	3057
Alphanumeric	4296	3391	2420	1852
Byte	2953	2331	1663	1273
Kanji	1817	1435	1024	784

Note: Maximum characters number can be different when using Mixed modes.

QR Code version can be set through options.version property. If no version is specified, the more suitable value will be used. Unless a specific version is required, this option is not needed.

QRCode.toDataURL('some text', { version: 2 }, function (err, url) {
  console.log(url)
})

Encoding modes

Modes can be used to encode a string in a more efficient way. A mode may be more suitable than others depending on the string content. A list of supported modes are shown in the table below:

Mode	Characters	Compression
Numeric	0, 1, 2, 3, 4, 5, 6, 7, 8, 9	3 characters are represented by 10 bits
Alphanumeric	0–9, A–Z (upper-case only), space, $, %, *, +, -, ., /, :	2 characters are represented by 11 bits
Kanji	Characters from the Shift JIS system based on JIS X 0208	2 kanji are represented by 13 bits
Byte	Characters from the ISO/IEC 8859-1 character set	Each characters are represented by 8 bits

Choose the right mode may be tricky if the input text is unknown. In these cases Byte mode is the best choice since all characters can be encoded with it. (See Multibyte characters) However, if the QR Code reader supports mixed modes, using Auto mode may produce better results.

Mixed modes

Mixed modes are also possible. A QR code can be generated from a series of segments having different encoding modes to optimize the data compression. However, switching from a mode to another has a cost which may lead to a worst result if it's not taken into account. See Manual mode for an example of how to specify segments with different encoding modes.

Auto mode

By default, automatic mode selection is used. The input string is automatically splitted in various segments optimized to produce the shortest possible bitstream using mixed modes. This is the preferred way to generate the QR Code.

For example, the string ABCDE12345678?A1A will be splitted in 3 segments with the following modes:

Segment	Mode
ABCDE	Alphanumeric
12345678	Numeric
?A1A	Byte

Any other combinations of segments and modes will result in a longer bitstream. If you need to keep the QR Code size small, this mode will produce the best results.

Manual mode

If auto mode doesn't work for you or you have specific needs, is also possible to manually specify each segment with the relative mode. In this way no segment optimizations will be applied under the hood. Segments list can be passed as an array of object:

  var QRCode = require('qrcode')

  var segs = [
    { data: 'ABCDEFG', mode: 'alphanumeric' },
    { data: '0123456', mode: 'numeric' }
  ]

  QRCode.toDataURL(segs, function (err, url) {
    console.log(url)
  })

Kanji mode

With kanji mode is possible to encode characters from the Shift JIS system in an optimized way. Unfortunately, there isn't a way to calculate a Shifted JIS values from, for example, a character encoded in UTF-8, for this reason a conversion table from the input characters to the SJIS values is needed. This table is not included by default in the bundle to keep the size as small as possible.

If your application requires kanji support, you will need to pass a function that will take care of converting the input characters to appropriate values.

An helper method is provided by the lib through an optional file that you can include as shown in the example below.

Note: Support for Kanji mode is only needed if you want to benefit of the data compression, otherwise is still possible to encode kanji using Byte mode (See Multibyte characters).

  var QRCode = require('qrcode')
  var toSJIS = require('qrcode/helper/to-sjis')

  QRCode.toDataURL(kanjiString, { toSJISFunc: toSJIS }, function (err, url) {
    console.log(url)
  })

With precompiled bundle:

<canvas id="canvas"></canvas>

<script src="/build/qrcode.min.js"></script>
<script src="/build/qrcode.tosjis.min.js"></script>
<script>
  var qrcodedraw = new qrcodelib.qrcodedraw()

  qrcodedraw.draw(document.getElementById('canvas'),
    'sample text', { toSJISFunc: qrcodelib.toSJIS }, function (error, canvas) {
    if (error) console.error(error)
    console.log('success!');
  })
</script>

Multibyte characters

Support for multibyte characters isn't present in the initial QR Code standard, but is possible to encode UTF-8 characters in Byte mode.

QR Codes provide a way to specify a different type of character set through ECI (Extended Channel Interpretation), but it's not fully implemented in this lib yet.

Most QR Code readers, however, are able to recognize multibyte characters even without ECI.

Note that a single Kanji/Kana or Emoji can take up to 4 bytes.

API

Browser

draw(canvasElement, text, options, cb(error, canvas))

Draws qr code symbol to canvas

canvasElement

Type: DOMElement

Canvas where to draw QR Code

text

Type: String|Array

Text to encode or a list of objects describing segments

options

version
Type: Number
QR Code version. If not specified the more suitable value will be calculated.
errorCorrectionLevel
Type: String Default: M
Error correction level. Possible values are low, medium, quartile, high or L, M, Q, H.
toSJISFunc
Type: Function
Helper function used internally to convert a kanji to its Shift JIS value. Provide this function if you need support for Kanji mode.

cb

Type: Function

Callback function called on finish

Server

draw(text, options, cb(error, canvas))

Draws qr code symbol to canvas Returns a node canvas object. See https://github.com/Automattic/node-canvas

QRCode.toDataURL(text, optional options, cb(error, dataURL));

Returns mime image/png data url for the 2d barcode.

QRCode.drawSvg(text, optional options, cb(error, svgString));

SVG output!

QRCode.save(path, text, optional options, cb(error, written));

Saves png to the path specified returns bytes written.

QRCode.drawText(text, optional options, cb)

Returns an ascii representation of the qrcode using unicode characters and ansi control codes for background control.

QRCode.drawBitArray(text, optional options, cb(error, bits, width));

Returns an array with each value being either 0 light or 1 dark and the width of each row. This is enough info to render a qrcode any way you want. =)

text

Type: String|Array

Text to encode or a list of objects describing segments

options

version
Type: Number
QR Code version. If not specified the more suitable value will be calculated.
errorCorrectionLevel
Type: String Default: M
Error correction level. Possible values are low, medium, quartile, high or L, M, Q, H.
toSJISFunc
Type: Function
Helper function used internally to convert a kanji to its Shift JIS value. Provide this function if you need support for Kanji mode.

cb

Type: Function

Callback function called on finish

GS1 QR Codes

There was a real good discussion here about them. but in short any qrcode generator will make gs1 compatible qrcodes, but what defines a gs1 qrcode is a header with metadata that describes your gs1 information.

https://github.com/soldair/node-qrcode/issues/45

Credits

This lib is based on "QRCode for JavaScript" which Kazuhiko Arase thankfully MIT licensed.

License

MIT

The word "QR Code" is registered trademark of: DENSO WAVE INCORPORATED

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0.7.3

7 years ago

0.7.2

7 years ago

0.7.1

7 years ago