Created
August 15, 2024 01:43
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| // Target object | |
| const target = { | |
| foo: 1, | |
| bar: 2, | |
| }; | |
| // Fallback object | |
| const fallback = { | |
| bar: 20, // This will be overridden by target's bar | |
| baz: 3, | |
| [Symbol('qux')]: 4, | |
| }; | |
| // Apply a proxy | |
| const proxy = new Proxy(target, { | |
| // Intercept property access | |
| get(target, property, receiver) { | |
| if (property in target) { | |
| return Reflect.get(target, property, receiver); | |
| } else if (property in fallback) { | |
| return Reflect.get(fallback, property, receiver); | |
| } | |
| return undefined; // Return undefined if not found | |
| }, | |
| // Intercept ownKeys to include keys from both target and fallback | |
| ownKeys(target) { | |
| const targetKeys = Reflect.ownKeys(target); | |
| const fallbackKeys = Reflect.ownKeys(fallback); | |
| return Array.from(new Set([...targetKeys, ...fallbackKeys])); | |
| }, | |
| // Intercept getOwnPropertyDescriptor to handle keys from both target and fallback | |
| getOwnPropertyDescriptor(target, property) { | |
| if (Reflect.has(target, property)) { | |
| return Reflect.getOwnPropertyDescriptor(target, property); | |
| } else if (Reflect.has(fallback, property)) { | |
| // Return a property descriptor that makes the property enumerable and configurable | |
| const descriptor = Reflect.getOwnPropertyDescriptor(fallback, property); | |
| return { | |
| ...descriptor, | |
| configurable: true, // Ensure the property can be modified or deleted | |
| enumerable: true, // Ensure the property shows up in enumerations | |
| }; | |
| } | |
| return undefined; | |
| } | |
| }); | |
| // Example usage | |
| console.log({ proxy }); | |
| // Deno Prints: { proxy: { foo: 1, bar: 2, baz: 3, [Symbol(qux)]: 4 } } | |
| // Node.js & Bun Prints: { proxy: { foo: 1, bar: 2 } } | |
| // Chrome & Safari Print: { proxy: Proxy {foo: 1, bar: 2} } | |
| // Firefox Prints: Object { proxy: Proxy } |
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