A function that convert an old Slate rule, to a single plugin object, containing the corresponding `validateNode` function

toValidateNode.js

// Converts an old rule definition to an individual plugin with a "validateNode" function
//
// rule: {
//   match,
//   validate,
//   normalize
// }
//
// returns {
//  validateNode
// }
function toValidateNode(rule) {
    return {
        validateNode: (node) => {
            if (!rule.match(node)) {
                return undefined;
            }
            const validationResult = rule.validate(node);
            if (validationResult == null) {
                return undefined;
            }

            return change => rule.normalize(change, node, validationResult);
        }
    };
}

Very nice! 👏