How to use

forEach

function

in

ObservableMap

render() {
    return (
      <App header = {CheckboxesStore.header}
        items = {CheckboxesStore.items}
        changeItems = {(label, checked) => transaction(() => CheckboxesStore.items.forEach((itemChecked, itemLabel) => CheckboxesStore.items.get(itemLabel).checked = checked))}
        changeItem = {(label, checked) => CheckboxesStore.items.get(label).checked = checked}
      />
    );
  }