function setupWebViewJavascriptBridge (callback) {
  if (window.WebViewJavascriptBridge) {
    return callback(window.WebViewJavascriptBridge)
  }
  if (window.WVJBCallbacks) {
    return window.WVJBCallbacks.push(callback)
  }
  window.WVJBCallbacks = [callback]
  let WVJBIframe = document.createElement('iframe')
  WVJBIframe.style.display = 'none'
  WVJBIframe.src = 'https://__bridge_loaded__'
  document.documentElement.appendChild(WVJBIframe)
  setTimeout(() => {
    document.documentElement.removeChild(WVJBIframe)
  }, 0)
}
function callhandler (name, data, callback) {
  setupWebViewJavascriptBridge(function (bridge) {
    bridge.callHandler(name, data, callback)
  })
}

callhandler(functionName: string, params: object, res => {})

registerhandler (name, callback) {
  // 安卓
  window[name] = res => {
   let data = JSON.parse(res)
   callback(data)
  }
  // IOS
  setupWebViewJavascriptBridge(function (bridge) {
    bridge.registerHandler(name, function (data, responseCallback) {
      callback(data, responseCallback)
    })
  })
}

window.HTTP_TEST.functionName()

window['functionName'] = res => {}