js 深度合并json对象

function isObject(obj) {
    return obj && typeof obj === 'object' && !Array.isArray(obj);
}

function deepMerge(target, ...sources) {
    if (!sources.length) return target;
    const source = sources.shift();

    if (isObject(target) && isObject(source)) {
        for (const key in source) {
            if (isObject(source[key])) {
                if (!target[key]) Object.assign(target, { [key]: {} });
                deepMerge(target[key], source[key]);
            } else {
                Object.assign(target, { [key]: source[key] });
            }
        }
    }

    return deepMerge(target, ...sources);
}

// 使用示例
const obj1 = { a: 1, b: { c: 2 } };
const obj2 = { b: { d: 3 }, e: 4 };
const mergedObj = deepMerge({}, obj1, obj2);

console.log(mergedObj); // 输出: { a: 1, b: { c: 2, d: 3 }, e: 4 }

function deepMerge(target, ...sources) {
    const visited = new WeakSet();

    function merge(target, source) {
        if (isObject(target) && isObject(source)) {
            if (visited.has(target) || visited.has(source)) {
                return; // 避免循环引用
            }
            visited.add(target);
            visited.add(source);

            for (const key in source) {
                if (isObject(source[key])) {
                    if (!target[key]) Object.assign(target, { [key]: {} });
                    merge(target[key], source[key]);
                } else {
                    Object.assign(target, { [key]: source[key] });
                }
            }
        }
    }

    sources.forEach(source => merge(target, source));
    return target;
}