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This article introduces the relevant knowledge of "what is the global object in nodejs". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

In Node.js, a .js file is a complete scope (module, module). Therefore, the variables declared by var are valid only in the current .js file, not globally. The global global object is independent of all .js (module, modules).

The top-level global object in the browser is the variable declared by window,var that is bound to the window object by default.

1. Definition of global object

Concept: objects that can be accessed anywhere in the program are called global objects. The properties of the object are called global variables.

2. Summary of global variables in NodeJS

Here we summarize the global variables that we often use in nodejs.

2.1 Buffer Class

Buffer, also known as a "buffer", its function is to open up an area in memory to store binary data.

2.2 _ _ dirname

_ _ dirname, which returns the absolute path of the folder (directory) where the current module file is parsed.

Remember, _ _ dirname is not really a global variable.

2.3 _ _ filename

_ _ filename, which returns the absolute path after the current module file has been parsed.

Remember, _ _ filename is not really a global variable.

2.4 module

Remember, module is not really a global variable.

2.5 require ()

Remember that require () is not really a global variable.

2.6 exports

Remember, exports is not really a global variable.

2.7 setImmediate and clearImmediate

2.8setTimeout and clearTimeout

2.9 setInterval and clearInterval

2.10 console

For printing to standard output and standard error

2.11 process

The process object provides information about and controls the current Node.js process.

2.12 URL

URL is a utility for URL processing and parsing

2.13 events

The events module is Node's implementation of the publish / subscribe pattern (publish/subscribe). One object passes a message to another object through this module. This module provides a constructor through the EventEmitter attribute.

3. GlobalThis

3.1What is globalThis?

The JS language is increasingly used in a variety of environments. In addition to the most common browsers, it can also run on servers, smartphones and even robotic hardware.

Each environment has its own object model and provides different syntax to access global objects. For example, in a Web browser, global objects can be accessed through window,self or frames. However, in Node.js, these properties do not exist, and you must use global.

GlobalThis aims to integrate increasingly decentralized methods of accessing global objects by defining a standard global property. The proposal is incorporated into the ES2020 standard. This feature is already supported by all popular browsers, including Chrome 71 +, Firefox 65 +, and Safari 12.1 desktop. You can also use it in Node.js 12 +.

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