严格相等运算符将告诉您两个对象类型是否相等。然而,是否有一种方法来判断两个对象是否相等,就像Java中的哈希码值一样?

堆栈溢出问题JavaScript中有hashCode函数吗?类似于这个问题,但需要一个更学术的答案。上面的场景说明了为什么有必要有一个,我想知道是否有等效的解决方案。


当前回答

下面的一些解决方案在性能、功能和风格方面存在问题……它们没有经过充分的考虑,其中一些在不同的情况下失败了。我试图在自己的解决方案中解决这个问题,我非常感谢您的反馈:

http://stamat.wordpress.com/javascript-object-comparison/

//Returns the object's class, Array, Date, RegExp, Object are of interest to us
var getClass = function(val) {
    return Object.prototype.toString.call(val)
        .match(/^\[object\s(.*)\]$/)[1];
};

//Defines the type of the value, extended typeof
var whatis = function(val) {

    if (val === undefined)
        return 'undefined';
    if (val === null)
        return 'null';

    var type = typeof val;

    if (type === 'object')
        type = getClass(val).toLowerCase();

    if (type === 'number') {
        if (val.toString().indexOf('.') > 0)
            return 'float';
        else
        return 'integer';
    }

    return type;
   };

var compareObjects = function(a, b) {
    if (a === b)
        return true;
    for (var i in a) {
        if (b.hasOwnProperty(i)) {
            if (!equal(a[i],b[i])) return false;
        } else {
            return false;
        }
    }

    for (var i in b) {
        if (!a.hasOwnProperty(i)) {
            return false;
        }
    }
    return true;
};

var compareArrays = function(a, b) {
    if (a === b)
        return true;
    if (a.length !== b.length)
        return false;
    for (var i = 0; i < a.length; i++){
        if(!equal(a[i], b[i])) return false;
    };
    return true;
};

var _equal = {};
_equal.array = compareArrays;
_equal.object = compareObjects;
_equal.date = function(a, b) {
    return a.getTime() === b.getTime();
};
_equal.regexp = function(a, b) {
    return a.toString() === b.toString();
};
//  uncoment to support function as string compare
//  _equal.fucntion =  _equal.regexp;



/*
 * Are two values equal, deep compare for objects and arrays.
 * @param a {any}
 * @param b {any}
 * @return {boolean} Are equal?
 */
var equal = function(a, b) {
    if (a !== b) {
        var atype = whatis(a), btype = whatis(b);

        if (atype === btype)
            return _equal.hasOwnProperty(atype) ? _equal[atype](a, b) : a==b;

        return false;
    }

    return true;
};

其他回答

我写了一个运行在Node.js和浏览器上的小库,叫做compare.js。它提供了常见的比较运算符,例如==,!=,>,>=,<,<=和所有JavaScript数据类型的标识符。

例如,你可以用

cmp.eq(obj1, obj2);

这将检查是否相等(使用深度相等的方法)。否则,如果你这样做

cmp.id(obj1, obj2);

它将通过引用进行比较,从而检查标识。 您还可以在对象上使用<和>,它们表示子集和超集。

Compare.js被近700个单元测试覆盖,因此它应该不会有太多的bug;-)。

你可以在https://github.com/goloroden/compare.js上免费找到它,它是MIT许可下的开源软件。

const one={name:'mohit' , age:30};
//const two ={name:'mohit',age:30};
const two ={age:30,name:'mohit'};

function isEquivalent(a, b) {
// Create arrays of property names
var aProps = Object.getOwnPropertyNames(a);
var bProps = Object.getOwnPropertyNames(b);



// If number of properties is different,
// objects are not equivalent
if (aProps.length != bProps.length) {
    return false;
}

for (var i = 0; i < aProps.length; i++) {
    var propName = aProps[i];

    // If values of same property are not equal,
    // objects are not equivalent
    if (a[propName] !== b[propName]) {
        return false;
    }
}

// If we made it this far, objects
// are considered equivalent
return true;
}

console.log(isEquivalent(one,two))

如果两个对象的所有属性都具有相同的值,并且所有嵌套对象和数组都递归地具有相同的值,那么将它们视为相等是很有用的。我也认为以下两个对象是相等的:

var a = {p1: 1};
var b = {p1: 1, p2: undefined};

类似地,数组可以有“缺失”元素和未定义的元素。我也会同样对待它们:

var c = [1, 2];
var d = [1, 2, undefined];

函数:实现等式定义的函数:

function isEqual(a, b) {
    if (a === b) {
        return true;
    }

    if (generalType(a) != generalType(b)) {
        return false;
    }

    if (a == b) {
        return true;
    }

    if (typeof a != 'object') {
        return false;
    }

    // null != {}
    if (a instanceof Object != b instanceof Object) {
        return false;
    }

    if (a instanceof Date || b instanceof Date) {
        if (a instanceof Date != b instanceof Date ||
            a.getTime() != b.getTime()) {
            return false;
        }
    }

    var allKeys = [].concat(keys(a), keys(b));
    uniqueArray(allKeys);

    for (var i = 0; i < allKeys.length; i++) {
        var prop = allKeys[i];
        if (!isEqual(a[prop], b[prop])) {
            return false;
        }
    }
    return true;
}

源代码(包括辅助函数,generalType和uniqueArray): 这里是单元测试和测试运行器。

我已经实现了一个方法,它接受两个json,并使用递归检查它们的键是否具有相同的值。 我用另一个问题来解决这个问题。

const arraysEqual = (a, b) => { if (a === b) return true; if (a === null || b === null) return false; if (a.length !== b.length) return false; // If you don't care about the order of the elements inside // the array, you should sort both arrays here. for (let i = 0; i < a.length; ++i) { if (a[i] !== b[i]) return false; } return true; }; const jsonsEqual = (a, b) => { if(typeof a !== 'object' || typeof b !== 'object') return false; if (Object.keys(a).length === Object.keys(b).length) { // if items have the same size let response = true; for (let key in a) { if (!b[key]) // if not key response = false; if (typeof a[key] !== typeof b[key]) // if typeof doesn't equals response = false; else { if (Array.isArray(a[key])) // if array response = arraysEqual(a[key], b[key]); else if (typeof a[key] === 'object') // if another json response = jsonsEqual(a[key], b[key]); else if (a[key] !== b[key]) // not equals response = false; } if (!response) // return if one item isn't equal return false; } } else return false; return true; }; const json1 = { a: 'a', b: 'asd', c: [ '1', 2, 2.5, '3', { d: 'asd', e: [ 1.6, { f: 'asdasd', g: '123' } ] } ], h: 1, i: 1.2, }; const json2 = { a: 'nops', b: 'asd' }; const json3 = { a: 'h', b: '484', c: [ 3, 4.5, '2ss', { e: [ { f: 'asdasd', g: '123' } ] } ], h: 1, i: 1.2, }; const result = jsonsEqual(json1,json2); //const result = jsonsEqual(json1,json3); //const result = jsonsEqual(json1,json1); if(result) // is equal $('#result').text("Jsons are the same") else $('#result').text("Jsons aren't equals") <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <div id="result"></div>

这是一个通用的相等检查函数,它接收数组元素作为输入,并将它们相互比较。适用于所有类型的元素。

const isEqual = function(inputs = []) {
  // Checks an element if js object.
  const isObject = function(data) {
    return Object.prototype.toString.call(data) === '[object Object]';
  };
  // Sorts given object by its keys.
  const sortObjectByKey = function(obj) {
    const self = this;
    if (!obj) return {};
    return Object.keys(obj).sort().reduce((initialVal, item) => {
      initialVal[item] = !Array.isArray(obj[item]) &&
        typeof obj[item] === 'object'
        ? self.objectByKey(obj[item])
        : obj[item];
      return initialVal;
    }, {});
  };

  // Checks equality of all elements in the input against each other. Returns true | false
  return (
    inputs
      .map(
        input =>
          typeof input == 'undefined'
            ? ''
            : isObject(input)
                ? JSON.stringify(sortObjectByKey(input))
                : JSON.stringify(input)
      )
      .reduce(
        (prevValue, input) =>
          prevValue === '' || prevValue === input ? input : false,
        ''
      ) !== false
  );
};

// Tests (Made with Jest test framework.)
test('String equality check', () => {
  expect(isEqual(['murat'])).toEqual(true);
  expect(isEqual(['murat', 'john', 'doe'])).toEqual(false);
  expect(isEqual(['murat', 'murat', 'murat'])).toEqual(true);
});

test('Float equality check', () => {
  expect(isEqual([7.89, 3.45])).toEqual(false);
  expect(isEqual([7, 7.50])).toEqual(false);
  expect(isEqual([7.50, 7.50])).toEqual(true);
  expect(isEqual([7, 7])).toEqual(true);
  expect(isEqual([0.34, 0.33])).toEqual(false);
  expect(isEqual([0.33, 0.33])).toEqual(true);
});

test('Array equality check', () => {
  expect(isEqual([[1, 2, 3], [1, 2, 3]])).toEqual(true);
  expect(isEqual([[1, 3], [1, 2, 3]])).toEqual(false);
  expect(isEqual([['murat', 18], ['murat', 18]])).toEqual(true);
});

test('Object equality check', () => {
  let obj1 = {
    name: 'murat',
    age: 18
  };
  let obj2 = {
    name: 'murat',
    age: 18
  };
  let obj3 = {
    age: 18,
    name: 'murat'
  };
  let obj4 = {
    name: 'murat',
    age: 18,
    occupation: 'nothing'
  };
  expect(isEqual([obj1, obj2])).toEqual(true);
  expect(isEqual([obj1, obj2, obj3])).toEqual(true);
  expect(isEqual([obj1, obj2, obj3, obj4])).toEqual(false);
});

test('Weird equality checks', () => {
  expect(isEqual(['', {}])).toEqual(false);
  expect(isEqual([0, '0'])).toEqual(false);
});

这里还有一个要点