Set breakpoint on Javascript object's property change

Data is the blood of a software application. Oftentimes, we need to know when and where a specific value is changed. That's easy for GDB in good old C world using hardware watchpoint. For Javascript, we can use setter/getter to catch the setting action.

function breakOnChange(obj, key) {
  let value = obj[key];

  Object.defineProperty(obj, key, {
    set(newValue) {
      value = newValue;
      debugger;
    },
    get() {
      return value;
    }
  });
};

let obj = {a: 1};
breakOnChange(obj, 'a');