JS Built-ins
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ObjectObject.sealbeginner

Object.seal() — returns the same object

📖 Usage Example
// Prevent adding/removing properties but allow value changes
const obj = Object.seal({ x: 1 })
obj.x = 99     // allowed — value can change
delete obj.x   // silently ignored
obj.x          // → 99

Use Object.seal() to prevent adding or deleting properties on an object while still allowing existing values to be updated.

Object.seal() — in-place mutation

Object.seal() modifies and returns the same object — it does not create a copy.

Challenge: Verify that Object.seal() returns the same object reference.

💡 Hints (1)
  • • Object.seal, freeze, and preventExtensions all return the modified object