Commonly used properties and methods of the process module in Node.js

Foreword

Although node does a lot of abstract work for the operating system, you can still interact with it directly, such as interacting with existing processes in the system and creating working sub-processes. Node is a thread for the event loop, but you can create other processes (threads) outside of this event loop to participate in the work.

If we are not dealing with command line tools, we may have few opportunities to use some methods or attributes in the process module. However, if you want to make a more complex build tool such as webpack or gulp, since the bash interface is a tool for direct communication with users, friendly input and output and complete prompts are very necessary.

Attributes

A table can roughly see what attributes the process has

We can use it directly in the code like this

console.log(porcess.platform) // darwin

Using argv will return an array of command lines. We can use the array to obtain the user's specific commands

console.log(process.argv); // [ '/usr/local/bin/node', '/Users/ali-130257n/www/weex-jackzoo/projects/demo.js', '-p', '-v' ]

Under normal circumstances, we want to get the last few parameters. The first two are not needed, we can

let args = process.argv.slice(2); console.log(args) // [ '-p', '-v' ]

Methods

process provides many methods. Generally we can use the following.

cwd: Returns the path to the working directory where the current script is running

abort: Ends the process immediately

nextTick: Specifies the task to run first in the next event loop

process supports some events. Through some events, we can make some friendly prompts or processing.

uncaughtException: When the current process throws an uncaught exception, the uncaughtException event will be triggered

message: accept messages from the parent process

rejectionHandled: use Used to capture the reject

generated by the promise error handling associated with it unhandledRejection: Similarly, this is used to capture the reject

const unhandledRejections = new Map(); process.on('unhandledRejection', (reason, p) => { unhandledRejections.set(p, reason); }); process.on('rejectionHandled', (p) => { unhandledRejections.delete(p); });

that is not associated with the promise error handling

warning: Start when the current process generates a warning

process.on('warning', (warning) => { console.warn(warning.name); // Print the warning name console.warn(warning.message); // Print the warning message console.warn(warning.stack); // Print the stack trace });

Summary

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