@netlify/build/lib/plugins/child/diff.js

Netlify build module

import { isDeepStrictEqual } from 'util';
import isPlainObj from 'is-plain-obj';
import rfdc from 'rfdc';
const clone = rfdc();
// Copy `netlifyConfig` so we can compare before/after mutating it
export const cloneNetlifyConfig = function (netlifyConfig) {
    return clone(netlifyConfig);
};
// Diff `netlifyConfig` before and after mutating it to retrieve an array of
// `configMutations` objects.
// We need to keep track of the changes on `netlifyConfig` so they can be
// processed later to:
//  - Warn plugin authors when mutating read-only properties
//  - Apply the change to `netlifyConfig` in the parent process so it can
//    run `@netlify/config` to normalize and validate the new values
// `configMutations` is passed to parent process as JSON
export const getConfigMutations = function (netlifyConfig, netlifyConfigCopy, event) {
    const configMutations = diffObjects(netlifyConfig, netlifyConfigCopy, []);
    return configMutations.map((configMutation) => getConfigMutation(configMutation, event));
};
// We only recurse over plain objects, not arrays. Which means array properties
// can only be modified all at once.
const diffObjects = function (objA, objB, parentKeys) {
    const allKeys = [...new Set([...Object.keys(objA), ...Object.keys(objB)])];
    return allKeys.flatMap((key) => {
        const valueA = objA[key];
        const valueB = objB[key];
        const keys = [...parentKeys, key];
        if (isPlainObj(valueA) && isPlainObj(valueB)) {
            return diffObjects(valueA, valueB, keys);
        }
        if (isDeepStrictEqual(valueA, valueB)) {
            return [];
        }
        return [{ keys, value: valueB }];
    });
};
const getConfigMutation = function ({ keys, value }, event) {
    const serializedKeys = keys.map(String);
    return {
        keys: serializedKeys,
        keysString: serializedKeys.join('.'),
        value,
        event,
    };
};