The answer
Use const plus Object.freeze together. const prevents reassignment of the variable, and Object.freeze prevents mutation of the object's properties. For nested objects, use a deep freeze function.
const with Objects and Arrays in JavaScript
How do you make a configuration object fully immutable in JavaScript?
More FAQs in const with Objects and Arrays in JavaScript
No. const prevents reassignment of the variable, but you can still mutate the object's properties (add, change, delete). Use Object.freeze for immutability.
const prevents reassignment of the variable binding. Object.freeze prevents mutation of the object itself (no property changes, additions, or deletions). They work at different levels: const is about the variable, freeze is about the value.
Shallow. Object.freeze prevents changes to the top-level object's properties, but nested objects can still be mutated. For deep immutability, you need a recursive deepFreeze function.
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