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

如果你的问题是检查两个对象是否相等,那么这个函数可能会有用

function equals(a, b) {
const aKeys = Object.keys(a)
const bKeys = Object.keys(b)
if(aKeys.length != bKeys.length) {
    return false
}
for(let i = 0;i < aKeys.length;i++) {
    if(aKeys[i] != bKeys[i]) {
        return false
    } 
}
for(let i = 0;i < aKeys.length;i++) {
    if(a[aKeys[i]] != b[bKeys[i]]) {
        return false
    }
}
return true
}

first we check if the length of the list of keys of these objects is the same, if not we return false to check if two objects are equal they must have the same keys(=names) and the same values of the keys, so we get all the keys of objA, and objB and then we check if they are equal once we find that tow keys are not equal then we return false and then when all the keys are equal then we loop through one of the keys of one of the objects and then we check if they are equal once they are not we return false and after the two loops finished this means they are equal and we return true NOTE: this function works with only objects with no functions

其他回答

如果你在AngularJS中工作,angular。Equals函数将确定两个对象是否相等。在Ember.js中使用isEqual。

角。equals -关于这个方法的更多信息,请参阅文档或源代码。它还对数组进行了深度比较。 js isEqual -关于这个方法的更多信息,请参阅文档或源代码。它不会对数组进行深度比较。

Var紫色=[{"紫色":"喝了"}]; Var drinking =[{"紫色":"喝了"}]; 如果(角。等于(紫色,喝)){ 文档。写(有dat); } < script src = " https://ajax.googleapis.com/ajax/libs/angularjs/1.4.5/angular.min.js " > < /脚本>

EDIT: This method is quite flawed, and is rife with its own issues. I don't recommend it, and would appreciate some down-votes! It is problematic because 1) Some things can not be compared (i.e. functions) because they can not be serialized, 2) It isn't a very fast method of comparing, 3) It has ordering issues, 4) It can have collision issues/false positives if not properly implemented, 5) It can't check for "exactness" (===), and instead is based of value equality, which is oftentimes not what is desired in a comparison method.

这个问题的一个简单解决方案是对JSON字符串进行排序(每个字符),但很多人没有意识到这一点。这通常也比这里提到的其他解决方案更快:

function areEqual(obj1, obj2) {
    var a = JSON.stringify(obj1), b = JSON.stringify(obj2);
    if (!a) a = '';
    if (!b) b = '';
    return (a.split('').sort().join('') == b.split('').sort().join(''));
}

关于这个方法的另一个有用的事情是,您可以通过向JSON传递一个“replace”函数来筛选比较。stringify函数(https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify#Example_of_using_replacer_parameter)。下面只比较所有命名为“derp”的对象键:

function areEqual(obj1, obj2, filter) {
    var a = JSON.stringify(obj1, filter), b = JSON.stringify(obj2, filter);
    if (!a) a = '';
    if (!b) b = '';
    return (a.split('').sort().join('') == b.split('').sort().join(''));
}
var equal = areEqual(obj1, obj2, function(key, value) {
    return (key === 'derp') ? value : undefined;
});

我需要模拟jQuery POST请求,因此对我来说重要的是两个对象具有相同的属性集(任何一个对象中都不缺少属性),并且每个属性值都是“相等的”(根据这个定义)。我不关心对象是否有不匹配的方法。

这是我将使用的,它应该足以满足我的特定要求:

function PostRequest() {
    for (var i = 0; i < arguments.length; i += 2) {
        this[arguments[i]] = arguments[i+1];
    }

    var compare = function(u, v) {
        if (typeof(u) != typeof(v)) {
            return false;
        }

        var allkeys = {};
        for (var i in u) {
            allkeys[i] = 1;
        }
        for (var i in v) {
            allkeys[i] = 1;
        }
        for (var i in allkeys) {
            if (u.hasOwnProperty(i) != v.hasOwnProperty(i)) {
                if ((u.hasOwnProperty(i) && typeof(u[i]) == 'function') ||
                    (v.hasOwnProperty(i) && typeof(v[i]) == 'function')) {
                    continue;
                } else {
                    return false;
                }
            }
            if (typeof(u[i]) != typeof(v[i])) {
                return false;
            }
            if (typeof(u[i]) == 'object') {
                if (!compare(u[i], v[i])) {
                    return false;
                }
            } else {
                if (u[i] !== v[i]) {
                    return false;
                }
            }
        }

        return true;
    };

    this.equals = function(o) {
        return compare(this, o);
    };

    return this;
}

像这样使用:

foo = new PostRequest('text', 'hello', 'html', '<p>hello</p>');
foo.equals({ html: '<p>hello</p>', text: 'hello' });

简而言之,这将检查两个变量是否相等,无论其类型如何。

function isSame (obj1, obj2) {
  const obj1Keys = Object.keys(obj1)
  const obj2Keys = Object.keys(obj2)

  return obj1Keys.length === obj2Keys.length && obj1Keys.every((key) => obj1[key] === obj2[key])
}

下面是stringify技巧的一个版本,它的输入较少,在很多情况下适用于简单的JSON数据比较。

var obj1Fingerprint = JSON.stringify(obj1).replace(/\{|\}/g,'').split(',').sort().join(',');
var obj2Fingerprint = JSON.stringify(obj2).replace(/\{|\}/g,'').split(',').sort().join(',');
if ( obj1Fingerprint === obj2Fingerprint) { ... } else { ... }