js trace function call

1// details can be found here: https://2ality.com/2017/11/proxy-method-calls.html
2
3function traceMethodCalls(obj) {
4    const handler = {
5        get(target, propKey, receiver) {
6            const targetValue = Reflect.get(target, propKey, receiver);
7            if (typeof targetValue === 'function') {
8                return function (...args) {
9                    console.log('CALL', propKey, args);
10                    return targetValue.apply(this, args); // (A)
11                }
12            } else {
13                return targetValue;
14            }
15        }
16    };
17    return new Proxy(obj, handler);    
18}
19
20const objWithFunction = {
21  methodA: (a) => { return a; }
22}
23
24const proxyWithTrace = traceMethodCalls(objWithFunction);