React Native MQTT模块`url`在Haste模块映射中不存在

Question

I want to explore this project https://github.com/mqttjs/MQTT.js within the React Native environment. So I did this:

react-native init myproject
npm install --save mqtt

Then I pasted this sample code from the mqttjs into my App.js a bit after the "Welcome to React Native" component.

var mqtt = require('mqtt')
var client  = mqtt.connect('mqtt://test.mosquitto.org')

client.on('connect', function () {
  client.subscribe('presence', function (err) {
    if (!err) {
      client.publish('presence', 'Hello mqtt')
    }
  })
})

client.on('message', function (topic, message) {
  // message is Buffer
  console.log(message.toString())
  client.end()
})

But when I run react-native run-android , I get a compilation error with a message like

Module url does not exist in the Haste module map

I tried replacing mqtt://test.mosquitto.org with a url to my own mosquitto broker with some of these values: mqtt://192.168.0.20 , tcp://192.168.0.20 , 192.168.0.20 . But all these still generated the same error.

What am I doing wrong?

Answer 1

您可以通过显式安装url模块来解决此问题：

npm install url