Proxy
Creates a new Proxy object that wraps a target object and intercepts operations defined by a handler
Syntax
new Proxy(target, handler)Parameters
| Parameter | Type | Description |
|---|---|---|
| target | object | The target object to wrap |
| handler | ProxyHandler | An object with trap functions for intercepting operations |
Return Value
A new Proxy object
Examples
const target = { name: 'Alice', age: 30 }
const proxy = new Proxy(target, {
get(obj, prop) {
console.log(`Accessing ${String(prop)}`)
return Reflect.get(obj, prop)
}
})
console.log(proxy.name) // logs 'Accessing name', then 'Alice'function createReactive<T extends object>(obj: T, onChange: () => void): T {
return new Proxy(obj, {
set(target, prop, value) {
const result = Reflect.set(target, prop, value)
onChange()
return result
}
})
}const validator = new Proxy({} as Record<string, number>, {
set(obj, prop, value) {
if (typeof value !== 'number') throw new TypeError('Value must be a number')
return Reflect.set(obj, prop, value)
}
})
validator.x = 42 // OK
// validator.y = 'hello' // throws TypeErrorUnderstanding Proxy
The Proxy method in JavaScript creates a new Proxy object that wraps a target object and intercepts operations defined by a handler. It belongs to the Proxy object and is one of the most widely used methods for working with proxy values in modern JavaScript and TypeScript applications.
The method signature is new Proxy(target, handler). It accepts 2 parameters: target, handler. When called, it returns a new proxy object. Understanding when and how to use Proxy() helps you write more expressive, readable code.
Common use cases for Proxy include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like proxy-revocable, reflect-get, reflect-set, enabling you to chain operations together for complex data manipulation pipelines.
Browser support for Proxy is excellent across all modern browsers including Chrome, Firefox, Safari, and Edge. It is also fully supported in Node.js and Deno. For older environments, transpilation with Babel or a polyfill may be needed.
Browser Compatibility
Supported in all modern browsers (Chrome, Firefox, Safari, Edge) and Node.js. Part of the ECMAScript standard.
Related Methods
Proxy.revocableCreates a revocable Proxy object, returning both the proxy and a revoke function that disables the proxy
Reflect.getGets the value of a property on an object, similar to target[propertyKey] but as a function
Reflect.setSets the value of a property on an object, similar to target[propertyKey] = value but as a function
More Proxy Methods
Other methods in the Proxy object
Related Tools
More Proxy Methods
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