Unable to get previous state in onChange plugin

I would like to create a plugin to save the editor content when onChange is fired. Following documentation, I would like to check previous document value before saving to database with:

if (prevValue.document !== newValue.document) {
  // Save to database
}

But I can’t find a way to get my previous value from the onChange plugin handler:

const SavePlugin = () => ({
  onChange: ({ value: newValue }, next) => {
    // How can I get previousValue ??
    if (prevValue.document !== newValue.document) {
      const content = JSON.stringify(newValue.toJSON());
      localStorage.setItem('content', content);
    }

    next();
  },
});

Is there a way to get the previous state value from the onChange plugin event handler?

[gdehmlow]

I think this is a question better suited for the Slack channel (https://slate-slack.herokuapp.com/).

But you could, say, leverage the closure of the SavePlugin like so:

const SavePlugin = () => {
  let previousValue = null;
  return {
    onChange: ({ value: newValue }, next) => {
      // How can I get previousValue ??
      if (previousValue.document !== newValue.document) {
        const content = JSON.stringify(newValue.toJSON());
        localStorage.setItem('content', content);
     }
     previousValue = newValue;
     next();
    },
  };
};

[damien-monni]

You can close the issue (y)