Why should you care?

Frameworks generate behavior from class metadata or object shapes.

See it live — copy this example

Paste into an HTML file or the browser console (F12). Use Run below when the live editor is available.

function logCalls(obj) {
  return new Proxy(obj, {
    get(target, key) {
      const val = target[key];
      if (typeof val === "function") {
        return function (...args) {
          console.log("call", key, args);
          return val.apply(target, args);
        };
      }
      return val;
    }
  });
}

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

What happened?

• Proxy wraps methods to log calls — a simple meta-programming pattern.

Practice next

1. Wrap object with logCalls proxy.
2. Log method name and args on each call.
3. Read decorators proposal status.
4. Add trap that blocks access to properties starting with underscore.
5. Auto-bind all methods on an object using meta wrapper.

Remember

Code about code Proxy/Reflect common tools Use sparingly

ScriptVerse API mock

DevTools mock layer proxies fetch targets to log calls during QA without changing app code.

Outcome: Meta-programming enables cross-cutting concerns like logging and access control.