提取两个对象（甚至嵌套对象）之间不同的键值是什么方法？答案

【问题标题】：extract key values that differ between two objects (even nested objects) what approach?提取两个对象（甚至嵌套对象）之间不同的键值是什么方法？
【发布时间】：2019-10-28 12:02:19
【问题描述】：

我想比较两个几乎总是具有相同属性的对象，并根据具有与第一个对象不同的值的属性创建一个新对象。在下面的示例中，我想检查 inputData 是否有任何与 currentData 不同的键：值。然后根据这些键和值创建一个新对象。希望它有意义吗？我应该有什么方法？一些递归的Oject.assign？传播操作？循环？

const currentData = {
  title: 'John',
  email: 'info@abc.com'
  address {
    street: 'myStreet 13'  
  }
}

const inputData = {
  title: 'Tom',
  email: 'info@abc.com',
  address {
    street: 'yourStreet 17'  
  }
}

结果应该是这样的：

const result = {
  title: 'Tom',
  address: {
    street: 'yourStreet 17'
  }   
}

【问题讨论】：

标签： javascript nested key javascript-objects

【解决方案1】：

您需要一个循环遍历对象的递归函数，大致如下：

function compareObjects(a, b) {
    // Assume they'll be the same
    let result = null;
    // Keep track of the keys we've seen
    let keys = new Set();
    for (const key in a) {
        keys.add(key);
        if (!(key in b)) {
            // You'll want to decide what to do here, use `undefined`?
        } else {
            const avalue = a[key];
            const bvalue = b[key];
            if (avalue !== bvalue) {
                const aIsObject = typeof avalue === "object";
                const bIsObject = typeof bvalue === "object";
                if (aIsObject && bIsObject) {
                    // Both are objects, recurse
                    const update = compareObjects(avalue, bvalue);
                    if (update) {
                        result = result || {};
                        result[key] = update;
                    }
                } else {
                    // Different values
                    result = result || {};
                    result[key] = bvalue;
                }
            }
        }
    }
    // Add in any that are in `b` but weren't in `a`
    for (const key in b) {
        if (!keys.has(key)) {
            result = result || {};
            result[key] = b[key];
        }
    }
    return result;
}

现场示例：

const currentData = {
    title: 'John',
    email: 'info@abc.com',
    address: {
        street: 'myStreet 13'  
    }
};

const inputData = {
    title: 'Tom',
    email: 'info@abc.com',
    address: {
        street: 'yourStreet 17'  
    }
};

function compareObjects(a, b) {
    // Assume they'll be the same
    let result = null;
    // Keep track of the keys we've seen
    let keys = new Set();
    for (const key in a) {
        keys.add(key);
        if (!(key in b)) {
            // You'll want to decide what to do here, use `undefined`?
        } else {
            const avalue = a[key];
            const bvalue = b[key];
            if (avalue !== bvalue) {
                const aIsObject = typeof avalue === "object";
                const bIsObject = typeof bvalue === "object";
                if (aIsObject && bIsObject) {
                    // Both are objects, recurse
                    const update = compareObjects(avalue, bvalue);
                    if (update) {
                        result = result || {};
                        result[key] = update;
                    }
                } else {
                    // Different values
                    result = result || {};
                    result[key] = bvalue;
                }
            }
        }
    }
    // Add in any that are in `b` but weren't in `a`
    for (const key in b) {
        if (!keys.has(key)) {
            result = result || {};
            result[key] = b[key];
        }
    }
    return result;
}

console.log(compareObjects(currentData, inputData));

【讨论】：