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JavaScript Book

The Global Object

The global object is an object that is always accessible and contains global variables, functions, and built‑in objects. In browsers, it is window; in Node.js, it is global; in modern JavaScript environments, globalThis provides a unified way to access the global object.

Key Points

Section titled “Key Points”
  • Global variables declared with var become properties of the global object.
  • Global functions like setTimeout, console, etc., are properties of the global object.
  • globalThis works across environments (browser, Node.js, Web Workers).

Code Example

Section titled “Code Example”
// In browser, this logs the window object
console.log(globalThis === window); // true (in browser)


// Global variable with var
var myGlobal = "Hello";
console.log(globalThis.myGlobal); // "Hello"


// Global function
function sayHi() {
  console.log("Hi");
}
globalThis.sayHi(); // "Hi"