docs: minor change for 09-emq-broker.md (#13352)

docs-en/20-third-party/09-emq-broker.md

@@ -21,17 +21,17 @@ Depending on the current operating system, users can download the installation p
 ### Take the Docker installation of TDengine as an example
 
 ```bash
-    docker exec -it tdengine bash
-    taos
+docker exec -it tdengine bash
+taos
 ```
 
 ### Create Database and Table
 
 ```sql
-    CREATE DATABASE test;
-    USE test;
+CREATE DATABASE test;
+USE test;
 
-    CREATE TABLE sensor_data (ts timestamp, temperature float, humidity float, volume float, PM10 float, pm25 float, SO2 float, NO2 float, CO float, sensor_id NCHAR(255), area TINYINT, coll_time timestamp);
+CREATE TABLE sensor_data (ts timestamp, temperature float, humidity float, volume float, PM10 float, pm25 float, SO2 float, NO2 float, CO float, sensor_id NCHAR(255), area TINYINT, coll_time timestamp);
 ```
 
 Note: The table schema is based on the blog [(In Chinese) Data Transfer, Storage, Presentation, EMQX + TDengine Build MQTT IoT Data Visualization Platform](https://www.taosdata.com/blog/2020/08/04/1722.html) as an example. Subsequent operations are carried out with this blog scenario too. Please modify it according to your actual application scenario.
@@ -81,21 +81,21 @@ Edit the resource configuration to add the key/value pairing for Authorization.
 ## Compose program to mock data
 
 ```javascript
-    // mock.js
-    const mqtt = require('mqtt')
-    const Mock = require('mockjs')
-    const EMQX_SERVER = 'mqtt://localhost:1883'
-    const CLIENT_NUM = 10
-    const STEP = 5000 // Data interval in ms
-    const AWAIT = 5000 // Sleep time after data be written once to avoid data writing too fast
-    const CLIENT_POOL = []
-    startMock()
-    function sleep(timer = 100) {
+// mock.js
+const mqtt = require('mqtt')
+const Mock = require('mockjs')
+const EMQX_SERVER = 'mqtt://localhost:1883'
+const CLIENT_NUM = 10
+const STEP = 5000 // Data interval in ms
+const AWAIT = 5000 // Sleep time after data be written once to avoid data writing too fast
+const CLIENT_POOL = []
+startMock()
+function sleep(timer = 100) {
   return new Promise(resolve => {
     setTimeout(resolve, timer)
   })
-    }
-    async function startMock() {
+}
+async function startMock() {
   const now = Date.now()
   for (let i = 0; i < CLIENT_NUM; i++) {
     const client = await createClient(`mock_client_${i}`)
@@ -119,12 +119,12 @@ Edit the resource configuration to add the key/value pairing for Authorization.
     await sleep(AWAIT)
   }
   console.log(`Done, use ${(Date.now() - now) / 1000}s`)
-    }
-    /**
+}
+/**
  * Init a virtual mqtt client
  * @param {string} clientId ClientID
  */
-    function createClient(clientId) {
+function createClient(clientId) {
   return new Promise((resolve, reject) => {
     const client = mqtt.connect(EMQX_SERVER, {
       clientId,
@@ -141,11 +141,11 @@ Edit the resource configuration to add the key/value pairing for Authorization.
       reject(e)
     })
   })
-    }
-    /**
-    * Generate mock data
-    */
-    function generateMockData() {
+}
+/**
+* Generate mock data
+*/
+function generateMockData() {
  return {
    "temperature": parseFloat(Mock.Random.float(22, 100).toFixed(2)),
    "humidity": parseFloat(Mock.Random.float(12, 86).toFixed(2)),
@@ -158,7 +158,7 @@ Edit the resource configuration to add the key/value pairing for Authorization.
    "area": Mock.Random.integer(0, 20),
    "ts": 1596157444170,
  }
-    }
+}
 ```
 
 Note: `CLIENT_NUM` in the code can be set to a smaller value at the beginning of the test to avoid hardware performance be not capable to handle a more significant number of concurrent clients.