Question on safety! Is qrcode generated by this library stored in the browser cache? I could not find the exact confirmation, yes or no (( Browsers write that the code from the memory cache rises ... but whether they keep it on the disk is not clear ((( This affects the safe use of secret data in the code!

This fix makes SVG code to be rendered correctly. Without this fix qrcode.js produces SVG image in "mirrored" way. Some of qr-code scanners can't handle such code. E.g.: Scanvi for iOS

The SVG support is used if the documentElement's tag name is "svg". I also made a demo page, it was tested in Chrome and Firefox, but it works a bit better in Firefox.

In main.js, I use these code to import qrcode.js

import "../lib/qrcode.min"

Then I package it use webpack, and open the html in browser, in the console:

Uncaught TypeError: Cannot read property '_android' of undefined

why? Can you help me? Thanks!

When I generate a QR-Code from a .vcf-file the code appears, but I can't scan it. I tried different Correction Levels, types and scanners. Here is a generated Example-Code:

Hi,

I need an example on your GitHub Page to use this library when I want to make an SVG image. I need this to make a QR code on SVG to enhance printing.

Best wishes,

Martin

I'm comparing the output of this script with the version produced by the qrencode unix tool and it seems for a sample I'm using, the js produces a QR code which is far larger than it needs to be (compared to the unix tool), which results in it being too detailed for my camera to recognise it.

I'm using a 734-character input to try it out, and the below images are the outputs of this library vs the unix tool (which I'm calling with docker run --rm giftig/qrencode -o - "$DATA")

Please ignore the content, it's a set of notes for myself. I considered writing some sample nonsense to post instead but I don't mind the internet knowing about my quest to do some electrical work on my house.

Forgive my ignorance of the details of how QR encoding works; I can't really speculate on what you're doing differently, but the result is clearly a far less space-optimised result. The latter image is recognised easily my by phone, and the former I have no doubt is a valid encoding of the same data, but is far too detailed to be viable.

bower.json has syntax error and bower can't install qrcode.js.

$ bower install qrcode.js=https://github.com/davidshimjs/qrcodejs.git
bower qrcode.js#*           not-cached https://github.com/davidshimjs/qrcodejs.git#*
bower qrcode.js#*              resolve https://github.com/davidshimjs/qrcodejs.git#*
bower qrcode.js#*             checkout master
bower qrcode.js#*           EMALFORMED Failed to read /var/folders/s2/j1hmfp3s2814bqll10pjny180000gn/T/hanai/bower/qrcode.js-6803-fUODrr/bower.json

Additional error details:
Unexpected token ]

Getting a Uncaught TypeError: Cannot read properties of undefined (reading 'length') error every-time a QR Code is created. Qr code does get created successfully, but what is this issue?

width: 74, height: 74, text: "http://wxh5.beta.hqjy.com/article/709?siteId=1&informationTypeId=139&informationType=2&provinceId=0", // colorDark: "#000", timer: null, colorLight: "#fff", correctLevel: this.$QRCode.CorrectLevel.L 是我生成的方式错了嘛？

After creating a QR Code, which is displayed and working properly, I get following error in the browser console:

DOMException: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported.

I am using the following code to generate the qr code:

    if (this.qrcode) {
      this.qrcode.clear();
    }

    this.qrcode = new QRCode(document.getElementById('qrcode'), {
      logo: logoLink,
      text: link,
      width: 256,
      height: 256,
      colorDark: '#000000',
      colorLight: '#ffffff',
      correctLevel: QRCode.CorrectLevel.H,
      logoWidth: undefined,
      logoHeight: undefined,
      logoBackgroundColor: '#ffffff',
      logoBackgroundTransparent: false,
    });

Any ideas on fixing this issue?

var qrcode = new QRCode(document.getElementById("qrcode"), {
  text: "01234567890abcd",
  correctLevel : QRCode.CorrectLevel.L
});
console.log(qrcode._oQRCode.getModuleCount());

Should log 21 but this logs 25. The reason is _getUTF8Length is comparing a length to a string and almost always ends up adding 3 (*):

	function _getUTF8Length(sText) {
		var replacedText = encodeURI(sText).toString().replace(/\%[0-9a-fA-F]{2}/g, 'a');
		return replacedText.length;
	}

I'm not 100% sure, but I think the following fix is correct:

507c507
< 		return replacedText.length + (replacedText.length != sText ? 3 : 0);
---
> 		return replacedText.length;

Happy to send a PR if there's agreement on this fix. Otherwise, I'll let people more familiar with this computation decide what's the correct fix.

* It doesn't add 3 if replacedText equals "", "1", "02", etc. which are degenerate cases.

When using the IE8 browser to generate the QR code, the form of the table tag is used. There is a problem here: to calculate the height of each cell, use the Math.floor() method. When there is a lot of content, because of the downward rounding, the actual generated QR code size will be much smaller than the actual displayed one. As a guess, the more content, the more severe the size distortion. It is recommended to use the style attribute when generating the table tag to fix the width and height instead of using the sum of the width and height calculated by the cell as the final width and height of the QR code. aHTML.push('</table style=“width:100%;height:100%">'); We can set the size of table`s parent node directly and Using margin to make size will cause some strange scenes

In the readme file, there is no CDN script to use it in the code. I have provided the CDN script so that developers can directly copy and paste it from the readme.

https://github.com/davidshimjs/qrcodejs/blob/04f46c6a0708418cb7b96fc563eacae0fbf77674/qrcode.js#L165

This will prevent android versions above 8.0.0 from generating data URI because google changed versioning format, they don't use semantic versioning in user agent anymore just integer: 9, 10, 11, 12

Best Regards.

One can easily test, that library draws wrong QR-codes for some special inputs like new QRCode(elem "\x80"); new QRCode(elem, "\u0800"); // samaritan letter alaf or any string, conatining chars with codes greater than 0xFFFF new QRCode(elem, "🔥");

The reasons are

• minor bounds check mistakes
• string method charCodeAt never returns codes greater than 0xFFFF, so one of the branches of QR8bitByte is never used!

One should notice, that js support for unicode strings is pretty poor: "🔥".length === 2, even though every human would say, this string has one 'character'.

P.S. qrcode.min.js should be updated also, i suppose, but i'm not sure which settings should be used, except smth like "preserve ie 6 compatibility"