Configuration
Read deployment configuration such as NODE_ENV or PORT from the environment.
Node.js · Const
process
process is a Node.js global object representing the currently running process. It exposes runtime information, environment data, command-line arguments, and process control APIs.
- Since
- v0.1.7
How it works
The globally available process object exposes information about and control over the Node.js process. Use its properties for runtime and environment details, and its methods and events for process-level behavior.
Syntax
processReturns
<Object> The process object.
Key points
- process is a globally available object representing the running Node.js process.
- The process global has existed since Node.js v0.1.7.
- The global-objects documentation directs readers to the dedicated process documentation for its complete API.
Common mistakes
- Although process is globally available, ordinary top-level variables in a Node.js module are not automatically global.
Example: Inspect the current process
console.log({pid: process.pid, node: process.version, mode: process.env.NODE_ENV ?? "development"});Prints selected information from the current Node.js process and reads an optional environment variable.
When to use it
CLI input
Inspect command-line arguments when building a CLI.
Diagnostics
Report runtime identity and diagnostics such as the process ID or Node.js version.
Interview questions
QWhat is the Node.js process object?
process is a global object that provides information about and control over the current Node.js process. Node.js applications can use it without importing it.
Follow-up: How would you inspect runtime metadata? Use properties such as process.version and process.versions.
QWhat does process.env provide?
process.env exposes the user environment as an object. Applications commonly read configuration from it, but should account for missing variables and deployment-specific values.
Follow-up: How can a program distinguish an unset variable from an empty one? Check explicitly for undefined and compare the resulting string with an empty value.
QWhat is process.argv used for?
process.argv is an array containing the command-line arguments passed when the Node.js process was launched. The application can inspect it to implement command-line options.
Follow-up: How would you parse complex options safely? Use a dedicated argument parser rather than relying on positional indexes throughout the application.
Related
process.argvprocess.envprocess.versionprocess.versionsprocess.pidprocess.exit()