Proxies

In the context of React JS, Proxies refer to a highly advanced feature of the JavaScript language that is used to define custom behavior for basic operations on objects, such as property lookup, assignment, enumeration, function invocation, etc. However, the term "Proxies" isn't exclusive to React, but is a JavaScript property that can be utilized within React.

The Proxy object is used to create a proxy for another object, which can intercept and redefine fundamental operations for that object. It can be used for a variety of sophisticated tasks such as logging and profiling, implementing interception, auto-populating objects, negative arrays indices, etc.

Here’s a very simple code snippet to demonstrate how one might use this:

```
let targetObject = {
message1: "hello",
message2: "everyone"
};

let handler = {
get: function(target, prop, receiver) {
return target[prop] ? target[prop] : "no message";
}
};

let proxy = new Proxy(targetObject, handler);

console.log(proxy.message1); // "hello"
console.log(proxy.random); // "no message", since 'random' doesn’t exist in 'targetObject'
```

In this example, 'targetObject' is the object we want to proxy. We define 'handler' with a get() method that provides our new property lookup behavior. A get() trap is a function that executes when someone tries to read a property of an object. Our 'handler' checks to see if the property exists on the targetObject, and if it doesn't, returns "no message".

Then we create the 'proxy' which is a Proxy object with the new behavior specified by 'handler'. From then on, any access to 'proxy' properties are intercepted by the Proxy object 'handler'.