node.js process.env用法及代码示例

process.env属性是流程模块的内置应用程序编程接口，用于获取用户环境。

用法:

process.env

返回值：此属性返回一个包含用户环境的对象。

以下示例说明了Node.js中process.env属性的使用：

范例1：

// Node.js program to demonstrate the 
// process.env Property 
   
// Include process module 
const process = require('process'); 
  
// Printing process.env property value 
console.log(process.env);

输出：

{ ALLUSERSPROFILE:'C:\\ProgramData',
  APPDATA:'C:\\Users\\gekcho\\AppData\\Roaming',
  cmake:'D:\\programfiles\\Cmake\\bin\\cmake.exe',
  CommonProgramFiles:'C:\\Program Files\\Common Files',
  'CommonProgramFiles(x86)':'C:\\Program Files (x86)\\Common Files',
  CommonProgramW6432:'C:\\Program Files\\Common Files',
  COMPUTERNAME:'gekchos_lappy',
  ComSpec:'C:\\Windows\\system32\\cmd.exe',
  DriverData:'C:\\Windows\\System32\\Drivers\\DriverData',
  GTK_BASEPATH:'C:\\Program Files (x86)\\GtkSharp\\2.12\\',
  HADOOP_HOME:
   'C:\\Users\\gekcho\\Downloads\\Compressed\\hadoop-3.1.0\\hadoop-3.1.0\\bin',
  HOMEDRIVE:'C:',
  HOMEPATH:'\\Users\\gekcho',
  JAVA_HOME:'C:\\Java\\jdk1.8.0_201',
  LOCALAPPDATA:'C:\\Users\\gekcho\\AppData\\Local',
  LOGONSERVER:'\\\\gekchos_lappy',
  MAGICK_HOME:'C:\\wamp64\\bin\\php\\php7.3.1\\ext\\ImageMagick',
  NUMBER_OF_PROCESSORS:'4',
  OneDrive:'C:\\Users\\gekcho\\OneDrive',
  OneDriveConsumer:'C:\\Users\\gekcho\\OneDrive',
  OS:'Windows_NT',
  Path:
   'C:\\wamp64\\bin\\php\\php7.3.1\\ext\\ImageMagick;
    C:\\Program Files (x86)\\Common Files\\Oracle\\Java\\javapath;
    C:\\Windows\\system32;C:\\Windows;C:\\Windows\\System32\\Wbem;
    C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\;
    C:\\Windows\\System32\\OpenSSH\\;D:\\programfiles\\Git\\cmd;
    D:\\programfiles\\Cmake\\bin;C:\\Program Files\\nodejs\\;
    C:\\Users\\gekcho\\Downloads\\Compressed\\hadoop-3.1.0\\hadoop-3.1.0\\bin;
    C:\\Java\\jdk1.8.0_201\\bin;
    C:\\Users\\gekcho\\Downloads\\Compressed\\spark-2.4.4-bin-hadoop2.7\\bin;
    C:\\Program Files (x86)\\GtkSharp\\2.12\\bin;
    C:\\Users\\gekcho\\AppData\\Local\\Microsoft\\WindowsApps;
    C:\\Users\\gekcho\\AppData\\Roaming\\npm',
  PATHEXT:'.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC',
  PROCESSOR_ARCHITECTURE:'AMD64',
  PROCESSOR_IDENTIFIER:'Intel64 Family 6 Model 142 Stepping 9, GenuineIntel',
  PROCESSOR_LEVEL:'6',
  PROCESSOR_REVISION:'8e09',
  ProgramData:'C:\\ProgramData',
  ProgramFiles:'C:\\Program Files',
  'ProgramFiles(x86)':'C:\\Program Files (x86)',
  ProgramW6432:'C:\\Program Files',
  PROMPT:'$P$G',
  PSModulePath:
   'C:\\Program Files\\WindowsPowerShell\\Modules;
    C:\\Windows\\system32\\WindowsPowerShell\\v1.0\\Modules',
  PUBLIC:'C:\\Users\\Public',
  python3:
   'C:\\Users\\gekcho\\AppData\\Local\\Programs\\Python\\Python37-32\\python.exe',
  SESSIONNAME:'Console',
  SPARK_HOME:
   'C:\\Users\\gekcho\\Downloads\\Compressed\\spark-2.4.4-bin-hadoop2.7',
  SystemDrive:'C:',
  SystemRoot:'C:\\Windows',
  TEMP:'C:\\Users\\gekcho\\AppData\\Local\\Temp',
  TMP:'C:\\Users\\gekcho\\AppData\\Local\\Temp',
  USERDOMAIN:'gekchos_lappy',
  USERDOMAIN_ROAMINGPROFILE:'gekchos_lappy',
  USERNAME:'gekcho',
  USERPROFILE:'C:\\Users\\gekcho',
  windir:'C:\\Windows' }

范例2：

// Node.js program to demonstrate the 
// process.env Property 
   
// Include process module 
const process = require('process'); 
  
// Printing process.env property value 
var no_env = 0; 
  
// Calling process.env 
var env = process.env; 
  
// Itterating through all returned data 
for (var key in env) { 
      
    // Print value 
    console.log(key + ":\t\t\t" + env[key]); 
    no_env++; 
} 
  
// Printing count 
console.log("total no of values available = "
            + no_env); 
  
// Accessing one by one 
console.log("operating system:" + env['OS']); 
console.log("alluserprofile:" + env['ALLUSERSPROFILE']); 
console.log("public directory:" + env['PUBLIC']);

输出：

ALLUSERSPROFILE:       C:\ProgramData
APPDATA:               C:\Users\gekcho\AppData\Roaming
cmake:                 D:\programfiles\Cmake\bin\cmake.exe
CommonProgramFiles:    C:\Program Files\Common Files
CommonProgramFiles(x86):C:\Program Files (x86)\Common Files
CommonProgramW6432:    C:\Program Files\Common Files
COMPUTERNAME:          gekchos_lappy
ComSpec:               C:\Windows\system32\cmd.exe
DriverData:            C:\Windows\System32\Drivers\DriverData
GTK_BASEPATH:          C:\Program Files (x86)\GtkSharp\2.12\
HADOOP_HOME:           C:\Users\gekcho\Downloads\Compressed\hadoop-3.1.0\hadoop-3.1.0\bin
HOMEDRIVE:             C:
HOMEPATH:              \Users\gekcho
JAVA_HOME:             C:\Java\jdk1.8.0_201
LOCALAPPDATA:          C:\Users\gekcho\AppData\Local
LOGONSERVER:           \\gekchos_lappy
MAGICK_HOME:           C:\wamp64\bin\php\php7.3.1\ext\ImageMagick
NUMBER_OF_PROCESSORS:  4
OneDrive:              C:\Users\gekcho\OneDrive
OneDriveConsumer:      C:\Users\gekcho\OneDrive
OS:                    Windows_NT
Path:                  C:\wamp64\bin\php\php7.3.1\ext\ImageMagick;
C:\Program Files (x86)\Common Files\Oracle\Java\javapath;
C:\Windows\system32;C:\Windows;
C:\Windows\System32\Wbem;
C:\Windows\System32\WindowsPowerShell\v1.0\;
C:\Windows\System32\OpenSSH\;D:\programfiles\Git\cmd;
D:\programfiles\Cmake\bin;C:\Program Files\nodejs\;
C:\Users\gekcho\Downloads\Compressed\hadoop-3.1.0\hadoop-3.1.0\bin;
C:\Java\jdk1.8.0_201\bin;
C:\Users\gekcho\Downloads\Compressed\spark-2.4.4-bin-hadoop2.7\bin;
C:\Program Files (x86)\GtkSharp\2.12\bin;
C:\Users\gekcho\AppData\Local\Microsoft\WindowsApps;
C:\Users\gekcho\AppData\Roaming\npm
PATHEXT:              .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC
PROCESSOR_ARCHITECTURE:AMD64
PROCESSOR_IDENTIFIER: Intel64 Family 6 Model 142 Stepping 9, GenuineIntel
PROCESSOR_LEVEL:      6
PROCESSOR_REVISION:   8e09
ProgramData:          C:\ProgramData
ProgramFiles:         C:\Program Files
ProgramFiles(x86):    C:\Program Files (x86)
ProgramW6432:         C:\Program Files
PROMPT:               $P$G
PSModulePath:         C:\Program Files\WindowsPowerShell\Modules;
                       C:\Windows\system32\WindowsPowerShell\v1.0\Modules
PUBLIC:               C:\Users\Public
python3:              C:\Users\gekcho\AppData\Local\Programs\Python\Python37-32\python.exe
SESSIONNAME:          Console
SPARK_HOME:           C:\Users\gekcho\Downloads\Compressed\spark-2.4.4-bin-hadoop2.7
SystemDrive:          C:
SystemRoot:           C:\Windows
TEMP:                 C:\Users\gekcho\AppData\Local\Temp
TMP:                  C:\Users\gekcho\AppData\Local\Temp
USERDOMAIN:           gekchos_lappy
USERDOMAIN_ROAMINGPROFILE:gekchos_lappy
USERNAME:             gekcho
USERPROFILE:          C:\Users\gekcho
windir:               C:\Windows
total no of values available = 46
operating system:Windows_NT
alluserprofile:C:\ProgramData
public directory:C:\Users\Public

范例3：

// Node.js program to demonstrate the 
// process.env Property 
   
// Include process module 
const process = require('process'); 
  
// Printing process.env property value 
var env = process.env; 
   
console.log("operating system:" + env.OS); 
console.log("alluserprofile:" + env.ALLUSERSPROFILE); 
console.log("public directory:" + env.PUBLIC); 
  
// Setting new data 
env.gekcho = "gekcho custom data"; 
console.log("stored in env.gekcho:" + env.gekcho); 
   
// Delete data 
delete env.gekcho 
console.log("stored in env.gekcho:" + env.gekcho);

输出：

operating system:Windows_NT
alluserprofile:C:\ProgramData
public directory:C:\Users\Public
stored in env.gekcho:gekcho custom data
stored in env.gekcho:undefined

注意：上面的程序将通过使用node filename.js命令。

参考： https://nodejs.org/api/process.html#process_process_env