js生成二维码qrcode

//在项目文件夹中执行：
npm install --save qrcode
//或者，将其全局安装以使用qrcode命令行来保存qrcode图像或生成可在终端中查看的图像。
npm install -g qrcode

Usage: qrcode [options] 

QR Code options:
  -v, --version  QR Code symbol version (1 - 40)
  -e, --error    Error correction level            [choices: "L", "M", "Q", "H"]
  -m, --mask     Mask pattern (0 - 7)

Renderer options:
  -t, --type        Output type                  [choices: "png", "svg", "utf8"]
  -w, --width       Image width (px)
  -s, --scale       Scale factor
  -q, --qzone       Quiet zone size
  -l, --lightcolor  Light RGBA hex color
  -d, --darkcolor   Dark RGBA hex color

Options:
  -o, --output  Output file
  -h, --help    Show help                                              [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

  
    
     
  



// index.js -> bundle.js
var QRCode = require('qrcode')
var canvas = document.getElementById('canvas')
 
QRCode.toCanvas(canvas, 'sample text', function (error) {
  if (error) console.error(error)
  console.log('success!');
})

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

//可以使用Promises和Async / Await来代替回调函数。



import QRCode from '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)
  }
}