两个对象。assign和Object spread只做浅合并。

这个问题的一个例子:

// No object nesting
const x = { a: 1 }
const y = { b: 1 }
const z = { ...x, ...y } // { a: 1, b: 1 }

输出是您所期望的。然而,如果我尝试这样做:

// Object nesting
const x = { a: { a: 1 } }
const y = { a: { b: 1 } }
const z = { ...x, ...y } // { a: { b: 1 } }

而不是

{ a: { a: 1, b: 1 } }

你得到

{ a: { b: 1 } }

X被完全覆盖,因为扩展语法只覆盖了一层。这与Object.assign()相同。

有办法做到这一点吗?


当前回答

如果您想合并多个普通对象(不要修改输入对象)。基于对象。分配polyfill

function isPlainObject(a) { return (!!a) && (a.constructor === Object); } function merge(target) { let to = Object.assign({}, target); for (let index = 1; index < arguments.length; index++) { let nextSource = arguments[index]; if (nextSource !== null && nextSource !== undefined) { for (let nextKey in nextSource) { // Avoid bugs when hasOwnProperty is shadowed if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) { if (isPlainObject(to[nextKey]) && isPlainObject(nextSource[nextKey])) { to[nextKey] = merge(to[nextKey], nextSource[nextKey]); } else { to[nextKey] = nextSource[nextKey]; } } } } } return to; } // Usage var obj1 = { a: 1, b: { x: 2, y: { t: 3, u: 4 } }, c: "hi" }; var obj2 = { b: { x: 200, y: { u: 4000, v: 5000 } } }; var obj3 = { c: "hello" }; console.log("result", merge(obj1, obj2, obj3)); console.log("obj1", obj1); console.log("obj2", obj2); console.log("obj3", obj3);

如果你想合并有限的深度

function isPlainObject(a) { return (!!a) && (a.constructor === Object); } function merge(target) { let to = Object.assign({}, target); const hasDepth = arguments.length > 2 && typeof arguments[arguments.length - 1] === 'number'; const depth = hasDepth ? arguments[arguments.length - 1] : Infinity; const lastObjectIndex = hasDepth ? arguments.length - 2 : arguments.length - 1; for (let index = 1; index <= lastObjectIndex; index++) { let nextSource = arguments[index]; if (nextSource !== null && nextSource !== undefined) { for (let nextKey in nextSource) { // Avoid bugs when hasOwnProperty is shadowed if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) { if (depth > 0 && isPlainObject(to[nextKey]) && isPlainObject(nextSource[nextKey])) { to[nextKey] = merge(to[nextKey], nextSource[nextKey], depth - 1); } else { to[nextKey] = nextSource[nextKey]; } } } } } return to; } // Usage var obj1 = { a: 1, b: { x: 2, y: { t: 3, u: 4, z: {zzz: 100} } }, c: "hi" }; var obj2 = { b: { y: { u: 4000, v: 5000, z: {} } } }; var obj3 = { c: "hello" }; console.log('deep 0', merge(obj1, obj2, obj3, 0)); console.log('deep 1', merge(obj1, obj2, obj3, 1)); console.log('deep 2', merge(obj1, obj2, obj3, 2)); console.log('deep 2', merge(obj1, obj2, obj3, 4));

其他回答

deepmerge npm包似乎是解决这个问题使用最广泛的库: https://www.npmjs.com/package/deepmerge

下面的函数对对象进行深度复制,它涵盖了复制原语、数组以及对象

 function mergeDeep (target, source)  {
    if (typeof target == "object" && typeof source == "object") {
        for (const key in source) {
            if (source[key] === null && (target[key] === undefined || target[key] === null)) {
                target[key] = null;
            } else if (source[key] instanceof Array) {
                if (!target[key]) target[key] = [];
                //concatenate arrays
                target[key] = target[key].concat(source[key]);
            } else if (typeof source[key] == "object") {
                if (!target[key]) target[key] = {};
                this.mergeDeep(target[key], source[key]);
            } else {
                target[key] = source[key];
            }
        }
    }
    return target;
}

另一个使用递归的变体,希望你觉得有用。

const merge = (obj1, obj2) => {

    const recursiveMerge = (obj, entries) => {
         for (const [key, value] of entries) {
            if (typeof value === "object") {
               obj[key] = obj[key] ? {...obj[key]} : {};
               recursiveMerge(obj[key], Object.entries(value))
            else {
               obj[key] = value;
            }
          }

          return obj;
    }

    return recursiveMerge(obj1, Object.entries(obj2))
}

这是我刚刚写的另一个支持数组的程序。它把它们连接起来。

function isObject(obj) {
    return obj !== null && typeof obj === 'object';
}


function isPlainObject(obj) {
    return isObject(obj) && (
        obj.constructor === Object  // obj = {}
        || obj.constructor === undefined // obj = Object.create(null)
    );
}

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

    if(Array.isArray(target)) {
        if(Array.isArray(source)) {
            target.push(...source);
        } else {
            target.push(source);
        }
    } else if(isPlainObject(target)) {
        if(isPlainObject(source)) {
            for(let key of Object.keys(source)) {
                if(!target[key]) {
                    target[key] = source[key];
                } else {
                    mergeDeep(target[key], source[key]);
                }
            }
        } else {
            throw new Error(`Cannot merge object with non-object`);
        }
    } else {
        target = source;
    }

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

我用es6做这个方法进行深度赋值。

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

function deepAssign(...objs) {
    if (objs.length < 2) {
        throw new Error('Need two or more objects to merge')
    }

    const target = objs[0]
    for (let i = 1; i < objs.length; i++) {
        const source = objs[i]
        Object.keys(source).forEach(prop => {
            const value = source[prop]
            if (isObject(value)) {
                if (target.hasOwnProperty(prop) && isObject(target[prop])) {
                    target[prop] = deepAssign(target[prop], value)
                } else {
                    target[prop] = value
                }
            } else if (Array.isArray(value)) {
                if (target.hasOwnProperty(prop) && Array.isArray(target[prop])) {
                    const targetArray = target[prop]
                    value.forEach((sourceItem, itemIndex) => {
                        if (itemIndex < targetArray.length) {
                            const targetItem = targetArray[itemIndex]

                            if (Object.is(targetItem, sourceItem)) {
                                return
                            }

                            if (isObject(targetItem) && isObject(sourceItem)) {
                                targetArray[itemIndex] = deepAssign(targetItem, sourceItem)
                            } else if (Array.isArray(targetItem) && Array.isArray(sourceItem)) {
                                targetArray[itemIndex] = deepAssign(targetItem, sourceItem)
                            } else {
                                targetArray[itemIndex] = sourceItem
                            }
                        } else {
                            targetArray.push(sourceItem)
                        }
                    })
                } else {
                    target[prop] = value
                }
            } else {
                target[prop] = value
            }
        })
    }

    return target
}