javascript / expert
Snippet
Recursive Proxy for Deep Immutability
Standard Object.freeze is shallow. By using a Recursive Proxy, we can intercept access to nested objects and wrap them in their own read-only proxies dynamically, ensuring true deep immutability without upfront traversal costs.
snippet.js
javascript
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const deepFreeze = (obj) => {return new Proxy(obj, {get(target, prop) {const value = Reflect.get(target, prop);return (value && typeof value === 'object') ? deepFreeze(value) : value;},set() {throw new Error('This object is read-only');},deleteProperty() {throw new Error('This object is read-only');}});};const config = deepFreeze({ api: { endpoint: 'v1' } });config.api.endpoint = 'v2'; // Throws Error
nextjs
Breakdown
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get(target, prop) { ... }
Intercepts property access to check if the returned value should also be proxied.
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deepFreeze(value) : value;
Recursively wraps nested objects in a proxy only when they are accessed (lazy evaluation).
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set() { throw new Error(...); }
Explicitly prevents any modifications to the object properties.