❗global var / function is global object property❗️
🚧 under construction
(side effect)
global var/ global function are implemented as global object property❗
❗global var is a global object property, and vice versa.
⚖️ compare： module scope - no module-wide scope object.
const { log } = console;
const isCurrentlyInGlobalScope = () => this === globalThis;
// log( prop ); // ReferenceError: (property is not hoisted) ⛔
log( topLevelVar ); // undefined : (var is hoisted but uninitialized)
// ⭐️ a global object property is like a global var (but not hoisted)
globalThis.prop = 42; // // define new property
log(prop, typeof prop); // 42, number // it acts like a global var
prop = 36; // // we can change it
console.log(globalThis.prop); // 36 // change will reflect on global object
// ⭐️ a global var is a global object property
// ❗ but in Node.js:
// • top-level scope is NOT global scope
// • top-level var will NOT be reflected in global/module context.
var topLevelVar = 'hello';
log(globalThis.topLevelVar); // undefined❗
log(module.exports.topLevelVar); // undefined❗
// log
;[
globalThis === global, // true
// current context
isCurrentlyInGlobalScope(), // false
this === module.exports, // true
].forEach(x => console.log(x));Previousaccessing var before declaration gets undefined❗️Nextvar redeclaration applied even in strict mode❗️
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