How to determine if a function has been called without setting global variable

Question

I am looking for a good technique to get away from what I am tempted to do: to set a global variable.

The first time someone runs a function by clicking a button it

Answer 1

The correct approach is to use the Javascript Proxy APIs to trap the function calls using apply handler.

const initFun = (args) => {
  console.log('args', args);
}
const init = new Proxy(initFun, {
  apply(target, thisArg, args){
    target.calls = target.calls ? target.calls + 1 : 1;
    return target.apply(thisArg, args);
  }
});

init('hi');
console.log(init.calls); // 1
init('hello');
console.log(init.calls); // 2