function hex(buffer) {
  var hexCodes = []
  var view = new DataView(buffer)
  for (var i = 0; i < view.byteLength; i += 4) {
    var value = view.getUint32(i).toString(16)
    var padding = '00000000'
    var code = (padding + value).slice(-padding.length)
    hexCodes.push(code)
  }
  return hexCodes.join('')
}
async function sha(str) {
  var buffer = new TextEncoder('utf-8').encode(str)
  var hash = await crypto.subtle.digest('SHA-1', buffer)
  return hex(hash)
}
await sha('test')