humus-old/client/ui/hooks/use-property-change.js

// 3rd party.
import React, {useEffect, useState} from 'react';

export function usePropertyChange(object, property, defaultValue, reducer) {
  const [value, setValue] = useState(defaultValue);
  useEffect(() => {
    if (!object) {
      return;
    }
    const onValueChanged = () => {
      const newValue = object[property];
      setValue(reducer ? reducer(newValue) : newValue);
    };
    onValueChanged();
    object.on(`${property}Changed`, onValueChanged);
    return () => {
      object.off(`${property}Changed`, onValueChanged);
    };
  }, [object, value]);
  return value;
}