What is process env PORT in Node js

Question

what is process env PORT    3000 used for in Node js  I saw this somewhere    app set  port   process env PORT    3000     If it is used to set 3000 as the listening port  can I use this instead   app listen 3000     If not why

User · Accepted Answer

In many environments  e g  Heroku   and as a convention  you can set the environment variable PORT to tell your web server what port to listen on  So process env PORT    3000 means  whatever is in the environment variable PORT  or 3000 if there s nothing there  So you pass that to app listen  or to app set  port         and that makes your server able to accept a  quot what port to listen on quot  parameter from the environment  If you pass 3000 hard-coded to app listen    you re always listening on port 3000  which might be just for you  or not  depending on your requirements and the requirements of the environment in which you re running your server

User · Answer

When hosting your application on another service  like Heroku  Nodejitsu  and AWS   your host may independently configure the process env PORT variable for you  after all  your script runs in their environment  Amazon s Elastic Beanstalk does this  If you try to set a static port value like 3000 instead of process env PORT    3000 where 3000 is your static setting  then your application will result in a 500 gateway error because Amazon is configuring the port for you  This is a minimal Express application that will deploy on Amazon s Elastic Beanstalk  var express   require  express    var app   express     app get      function  req  res      res send  Hello World             use port 3000 unless there exists a preconfigured port var port   process env PORT    3000   app listen port

User · Answer

if you run node index js  Node will use 3000 If you run PORT 4444 node index js  Node will use process env PORT which equals to 4444 in this example  Run with sudo for ports below 1024

User · Answer

In some scenarios  port can only be designated by the environment and is saved in a user environment variable  Below is how node js apps work with it   The process object is a global that provides information about  and control over  the current Node js process  As a global  it is always available to Node js applications without using require      The process env property returns an object containing the user environment   An example of this object looks like       TERM   xterm-256color     SHELL    usr local bin bash     USER   maciej     PATH      bin   usr bin  bin  usr sbin  sbin  usr local bin     PWD    Users maciej     EDITOR   vim     SHLVL   1     HOME    Users maciej     LOGNAME   maciej          usr local bin node      For example   terminal  set a new user environment variable  not permanently  export MY TEST PORT 9999   app js  read the new environment variable from node app  console log process env MY TEST PORT    terminal  run the node app and get the value    node app js 9999

[node.js] What is process.env.PORT in Node.js?

Examples related to node.js

Examples related to express

Examples related to port