javascript / expert
Snippet
Structural Validation with Proxy Traps
The Proxy object allows you to create a wrapper for another object, intercepting fundamental operations like property assignment. By using the 'set' trap and 'Reflect' API, you can implement robust runtime type checking.
snippet.js
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const schema = { name: 'string', age: 'number' };const handler = {set(target, prop, value) {if (schema[prop] && typeof value !== schema[prop]) {throw new TypeError(`Invalid type for ${prop}`);}return Reflect.set(...arguments);}};const user = new Proxy({}, handler);user.name = 'Alice'; // Worksuser.age = 'none'; // Throws TypeError
Breakdown
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set(target, prop, value)
A trap for setting property values on the proxy object.
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Reflect.set(...arguments)
Standard way to perform the default action of assigning a value to a property.
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new Proxy({}, handler)
Constructs a proxy that uses the defined handler to intercept operations.