@slidoapp/qrcode
Advanced tools
Generate Quick Response (QR) codes using JavaScript in a browser, server side code, or using a command line tool.
Generate Quick Response (QR) codes using JavaScript in a browser, server side code, or using a command line tool.
Inside your project folder do:
npm install --save @slidoapp/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 @slidoapp/qrcode
Usage: qrcode [options] <input string>
QR Code options:
-v, --qversion QR Code symbol version (1 - 40) [number]
-e, --error Error correction level [choices: "L", "M", "Q", "H"]
-m, --mask Mask pattern (0 - 7) [number]
Renderer options:
-t, --type Output type [choices: "png", "svg", "utf8"]
-w, --width Image width (px) [number]
-s, --scale Scale factor [number]
-q, --qzone Quiet zone size [number]
-l, --lightcolor Light RGBA hex color
-d, --darkcolor Dark RGBA hex color
--small Output smaller QR code to terminal [boolean]
Options:
-o, --output Output file
-h, --help Show help [boolean]
--version Show version number [boolean]
Examples:
qrcode "some text" Draw in terminal window
qrcode -o out.png "some text" Save as png image
qrcode -d F00 -o out.png "some text" Use red as foreground color
If not specified, output type is guessed from file extension.
Recognized extensions are png, svg and txt.
The @slidoapp/qrcode can be used in browser through module bundlers like Browserify and Webpack or by including the precompiled bundle present in build/ folder.
<!-- index.html -->
<html>
<body>
<canvas id="canvas"></canvas>
<script src="bundle.js"></script>
</body>
</html>
// index.js -> bundle.js
var QRCode = require('@slidoapp/qrcode')
var canvas = document.getElementById('canvas')
QRCode.toCanvas(canvas, 'sample text', function (error) {
if (error) console.error(error)
console.log('success!');
})
<canvas id="canvas"></canvas>
<script src="/build/qrcode.js"></script>
<script>
QRCode.toCanvas(document.getElementById('canvas'), 'sample text', function (error) {
if (error) console.error(error)
console.log('success!');
})
</script>
If you install through npm, precompiled files will be available in node_modules/qrcode/build/ folder.
The precompiled bundle have support for Internet Explorer 10+, Safari 5.1+, and all evergreen browsers.
Require the module @slidoapp/qrcode
var QRCode = require('@slidoapp/qrcode')
QRCode.toDataURL('I am a pony!', function (err, url) {
console.log(url)
})
render a qrcode for the terminal
var QRCode = require('@slidoapp/qrcode')
QRCode.toString('I am a pony!',{type:'terminal'}, function (err, url) {
console.log(url)
})
Promises and Async/Await can be used in place of callback function.
import QRCode from '@slidoapp/qrcode'
// With promises
QRCode.toDataURL('I am a pony!')
.then(url => {
console.log(url)
})
.catch(err => {
console.error(err)
})
// With async/await
const generateQR = async text => {
try {
console.log(await QRCode.toDataURL(text))
} catch (err) {
console.error(err)
}
}
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)
})
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 size of the symbol.
For version 1 symbol size is 21x21 modules, for version 2 25x25 and so on up to 177x177 modules
for the largest symbol size.
The higher the version, the more data can be stored in the QR code and of course the bigger the symbol will be.
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 most 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)
})
Modes can be used to encode a string in a more efficient way.
A mode may be more suitable than the others depending on the data 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 |
Choosing 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 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.
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.
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('@slidoapp/qrcode')
var segs = [
{ data: 'ABCDEFG', mode: 'alphanumeric' },
{ data: '0123456', mode: 'numeric' }
]
QRCode.toDataURL(segs, function (err, url) {
console.log(url)
})
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('@slidoapp/qrcode')
var toSJIS = require('@slidoapp/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>
QRCode.toCanvas(document.getElementById('canvas'),
'sample text', { toSJISFunc: QRCode.toSJIS }, function (error) {
if (error) console.error(error)
console.log('success!')
})
</script>
QR Codes can hold arbitrary byte-based binary data. If you attempt to create a binary QR Code by first converting the data to a JavaScript string, it will fail to encode propery because string encoding adds additional bytes. Instead, you must pass a Uint8ClampedArray or compatible array, or a Node Buffer, as follows:
// Regular array example
// WARNING: Element values will be clamped to 0-255 even if your data contains higher values.
const QRCode = require('@slidoapp/qrcode')
QRCode.toFile(
'foo.png',
[{ data: [253,254,255], mode: 'byte' }],
...options...,
...callback...
)
// Uint8ClampedArray example
const QRCode = require('@slidoapp/qrcode')
QRCode.toFile(
'foo.png',
[{ data: new Uint8ClampedArray([253,254,255]), mode: 'byte' }],
...options...,
...callback...
)
// Node Buffer example
// WARNING: Element values will be clamped to 0-255 even if your data contains higher values.
const QRCode = require('@slidoapp/qrcode')
QRCode.toFile(
'foo.png',
[{ data: Buffer.from([253,254,255]), mode: 'byte' }],
...options...,
...callback...
)
TypeScript users: if you are using @types/qrcode, you will need to add a // @ts-ignore above the data segment because it expects data: string.
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.
Browser:
Server:
create(text, [options])Creates QR Code symbol and returns a qrcode object.
textType: String|Array
Text to encode or a list of objects describing segments.
optionsSee QR Code options.
returnsType: Object
// QRCode object
{
modules, // Bitmatrix class with modules data
version, // Calculated QR Code version
errorCorrectionLevel, // Error Correction Level
maskPattern, // Calculated Mask pattern
segments // Generated segments
}
toCanvas(canvasElement, text, [options], [cb(error)])toCanvas(text, [options], [cb(error, canvas)])Draws qr code symbol to canvas.
If canvasElement is omitted a new canvas is returned.
canvasElementType: DOMElement
Canvas where to draw QR Code.
textType: String|Array
Text to encode or a list of objects describing segments.
optionsSee Options.
cbType: Function
Callback function called on finish.
QRCode.toCanvas('text', { errorCorrectionLevel: 'H' }, function (err, canvas) {
if (err) throw err
var container = document.getElementById('container')
container.appendChild(canvas)
})
toDataURL(text, [options], [cb(error, url)])toDataURL(canvasElement, text, [options], [cb(error, url)])Returns a Data URI containing a representation of the QR Code image.
If provided, canvasElement will be used as canvas to generate the data URI.
canvasElementType: DOMElement
Canvas where to draw QR Code.
textType: String|Array
Text to encode or a list of objects describing segments.
optionstypeType: String
Default: image/png
Data URI format.
Possible values are: image/png, image/jpeg, image/webp.
rendererOpts.qualityType: Number
Default: 0.92
A Number between 0 and 1 indicating image quality if the requested type is image/jpeg or image/webp.
See Options for other settings.
cbType: Function
Callback function called on finish.
var opts = {
errorCorrectionLevel: 'H',
type: 'image/jpeg',
quality: 0.3,
margin: 1,
color: {
dark:"#010599FF",
light:"#FFBF60FF"
}
}
QRCode.toDataURL('text', opts, function (err, url) {
if (err) throw err
var img = document.getElementById('image')
img.src = url
})
toString(text, [options], [cb(error, string)])Returns a string representation of the QR Code.
textType: String|Array
Text to encode or a list of objects describing segments.
optionstypeType: String
Default: utf8
Output format.
Possible values are: terminal,utf8, and svg.
See Options for other settings.
cbType: Function
Callback function called on finish.
QRCode.toString('http://www.google.com', function (err, string) {
if (err) throw err
console.log(string)
})
create(text, [options])See create.
toCanvas(canvas, text, [options], [cb(error)])Draws qr code symbol to node canvas.
textType: String|Array
Text to encode or a list of objects describing segments.
optionsSee Options.
cbType: Function
Callback function called on finish.
toDataURL(text, [options], [cb(error, url)])Returns a Data URI containing a representation of the QR Code image.
Only works with image/png type for now.
textType: String|Array
Text to encode or a list of objects describing segments.
optionsSee Options for other settings.
cbType: Function
Callback function called on finish.
toString(text, [options], [cb(error, string)])Returns a string representation of the QR Code.
If choosen output format is svg it will returns a string containing xml code.
textType: String|Array
Text to encode or a list of objects describing segments.
optionstypeType: String
Default: utf8
Output format.
Possible values are: utf8, svg, terminal.
See Options for other settings.
cbType: Function
Callback function called on finish.
QRCode.toString('http://www.google.com', function (err, string) {
if (err) throw err
console.log(string)
})
toFile(path, text, [options], [cb(error)])Saves QR Code to image file.
If options.type is not specified, the format will be guessed from file extension.
Recognized extensions are png, svg, txt.
pathType: String
Path where to save the file.
textType: String|Array
Text to encode or a list of objects describing segments.
optionstypeType: String
Default: png
Output format.
Possible values are: png, svg, utf8.
rendererOpts.deflateLevel (png only)Type: Number
Default: 9
Compression level for deflate.
rendererOpts.deflateStrategy (png only)Type: Number
Default: 3
Compression strategy for deflate.
See Options for other settings.
cbType: Function
Callback function called on finish.
QRCode.toFile('path/to/filename.png', 'Some text', {
color: {
dark: '#00F', // Blue dots
light: '#0000' // Transparent background
}
}, function (err) {
if (err) throw err
console.log('done')
})
toFileStream(stream, text, [options])Writes QR Code image to stream. Only works with png format for now.
streamType: stream.Writable
Node stream.
textType: String|Array
Text to encode or a list of objects describing segments.
optionsSee Options.
versionType: Number
QR Code version. If not specified the more suitable value will be calculated.
errorCorrectionLevelType: String
Default: M
Error correction level.
Possible values are low, medium, quartile, high or L, M, Q, H.
maskPatternType: Number
Mask pattern used to mask the symbol.
Possible values are 0, 1, 2, 3, 4, 5, 6, 7.
If not specified the more suitable value will be calculated.
toSJISFuncType: Function
Helper function used internally to convert a kanji to its Shift JIS value.
Provide this function if you need support for Kanji mode.
marginType: Number
Default: 4
Define how much wide the quiet zone should be.
scaleType: Number
Default: 4
Scale factor. A value of 1 means 1px per modules (black dots).
smallType: Boolean
Default: false
Relevant only for terminal renderer. Outputs smaller QR code.
widthType: Number
Forces a specific width for the output image.
If width is too small to contain the qr symbol, this option will be ignored.
Takes precedence over scale.
color.darkType: String
Default: #000000ff
Color of dark module. Value must be in hex format (RGBA).
Note: dark color should always be darker than color.light.
color.lightType: String
Default: #ffffffff
Color of light module. Value must be in hex format (RGBA).
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
The source code is based on the QRCode for JavaScript by Kazuhiko Arase, licenced under MIT License.
Source code is licensed under MIT License.
The word "QR Code" is registered trademark of DENSO WAVE INCORPORATED in Japan and other countries.
FAQs
Generate Quick Response (QR) codes using JavaScript in a browser, server side code, or using a command line tool.
The npm package @slidoapp/qrcode receives a total of 532 weekly downloads. As such, @slidoapp/qrcode popularity was classified as not popular.
We found that @slidoapp/qrcode demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
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