Difference between global & globalThis

Source: Dev.to

Overview

global and globalThis both refer to JavaScript’s global object, but they differ in scope and compatibility across environments.

• global – Node.js‑specific. It is the top‑level object that contains built‑in functions such as console and setTimeout. It does not exist in browsers; accessing it there throws a ReferenceError.
• globalThis – Introduced in ES2020 as a standardized, cross‑platform way to access the global object. It works in browsers (window), Node.js (global), and Web Workers (self).

Environment‑specific globals (pre‑ES2020)

Before globalThis, writing universal JavaScript required a series of checks:

// Get the global object in a way that works across environments
function getGlobalObjectOldWay() {
  // Browser
  if (typeof window !== 'undefined') {
    return window;
  }
  // Node.js
  if (typeof global !== 'undefined') {
    return global;
  }
  // Web Worker
  if (typeof self !== 'undefined') {
    return self;
  }
  // Fallback (e.g., non‑strict function context)
  return this;
}

console.log('Old way (Node.js):', getGlobalObjectOldWay());

globalThis – the modern solution

globalThis provides a single, consistent reference to the global object across all JavaScript environments. In the global scope, this is equal to globalThis, making it easy to remember.

Comparison

References:

• MDN Web Docs – globalThis

When to use which

• Use globalThis for shared codebases (e.g., full‑stack projects) to avoid environment‑specific bugs.
• Use global only when you are explicitly writing Node.js‑only code.