解决微信小程序previewImage api不能预览base64的问题

js
function previewImg(e) {
  const url = e.currentTarget.dataset.url
 
  this.base64src(url, res => {
    wx.previewImage({
      current: res,
      urls: [res],
    })
  })
}
 
function base64src(base64data, cb) {
  const FILE_BASE_NAME = 'tmp_base64src' //自定义文件名
  const [, format, bodyData] = /data:image\/(\w+);base64,(.*)/.exec(base64data) || []
  if (!format) {
    return new Error('ERROR_BASE64SRC_PARSE')
  }
  const filePath = `${wx.env.USER_DATA_PATH}/${FILE_BASE_NAME}.${format}`
  const buffer = wx.base64ToArrayBuffer(bodyData)
  const fsm = wx.getFileSystemManager()
  fsm.writeFile({
    filePath,
    data: buffer,
    encoding: 'binary',
    success() {
      cb(filePath)
    },
    fail() {
      return new Error('ERROR_BASE64SRC_WRITE')
    },
  })
}