@cch137/format-utils/dist/deepmerge/index.js

A collection of utility modules for formatting and processing data

export function deepmerge(...objects) {
    const validObjects = objects.filter((obj) => obj != null);
    if (validObjects.length === 0) {
        return {};
    }
    if (validObjects.length === 1) {
        return { ...validObjects[0] };
    }
    const result = { ...validObjects[0] };
    const prototypeOfArray = Object.getPrototypeOf([]);
    const prototypeOfObject = Object.getPrototypeOf({});
    const isMergable = (o) => o &&
        typeof o === "object" &&
        Object.getPrototypeOf(o) === prototypeOfObject;
    const isArray = (o) => Array.isArray(o) && Object.getPrototypeOf(o) === prototypeOfArray;
    for (let i = 1; i < validObjects.length; i++) {
        const currentObj = validObjects[i];
        for (const key in currentObj) {
            if (Object.prototype.hasOwnProperty.call(currentObj, key)) {
                const currentValue = currentObj[key];
                const existingValue = result[key];
                if (currentValue === null || currentValue === undefined) {
                    result[key] = currentValue;
                    continue;
                }
                if (isMergable(existingValue) && isMergable(currentValue)) {
                    result[key] = deepmerge(existingValue, currentValue);
                }
                else {
                    if (isArray(currentValue)) {
                        result[key] = [...currentValue];
                    }
                    else if (isMergable(currentValue)) {
                        result[key] = { ...currentValue };
                    }
                    else {
                        result[key] = currentValue;
                    }
                }
            }
        }
    }
    return result;
}