JS Built-ins
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ObjectObject.isFrozenintermediate

Object.isFrozen() — after seal (not frozen)

📖 Usage Example
// Check if an object is frozen
const obj = { a: 1 }
Object.isFrozen(obj)    // → false
Object.freeze(obj)
Object.isFrozen(obj)    // → true

Use Object.isFrozen() to verify that an object is fully immutable (no additions, deletions, or value changes allowed).

Object.isFrozen() — sealed is NOT frozen

Object.seal() prevents adding/removing properties but allows modifying existing writable ones. So a sealed object with writable properties is not frozen.

Challenge: Show the difference between sealed and frozen objects using Object.isFrozen().

💡 Hints (1)
  • • seal is weaker than freeze — sealed objects can still be written to