var a = [1, 2, 3];
var b = [3, 2, 1];
var c = new Array(1, 2, 3);

alert(a == b + "|" + b == c);

demo

如何检查这些数组是否相等,并获得一个方法,如果它们相等,则返回true ?

jQuery是否为此提供了任何方法?


当前回答

jQuery就有这样的方法进行深层递归比较。

一个自主开发的通用严格的相等检查可以如下所示:

function deepEquals(obj1, obj2, parents1, parents2) {
    "use strict";
    var i;
    // compare null and undefined
    if (obj1 === undefined || obj2 === undefined || 
        obj1 === null || obj2 === null) {
        return obj1 === obj2;
    }

    // compare primitives
    if (typeof (obj1) !== 'object' || typeof (obj2) !== 'object') {
        return obj1.valueOf() === obj2.valueOf();
    }

    // if objects are of different types or lengths they can't be equal
    if (obj1.constructor !== obj2.constructor || (obj1.length !== undefined && obj1.length !== obj2.length)) {
        return false;
    }

    // iterate the objects
    for (i in obj1) {
        // build the parents list for object on the left (obj1)
        if (parents1 === undefined) parents1 = [];
        if (obj1.constructor === Object) parents1.push(obj1);
        // build the parents list for object on the right (obj2)
        if (parents2 === undefined) parents2 = [];
        if (obj2.constructor === Object) parents2.push(obj2);
        // walk through object properties
        if (obj1.propertyIsEnumerable(i)) {
            if (obj2.propertyIsEnumerable(i)) {
                // if object at i was met while going down here
                // it's a self reference
                if ((obj1[i].constructor === Object && parents1.indexOf(obj1[i]) >= 0) || (obj2[i].constructor === Object && parents2.indexOf(obj2[i]) >= 0)) {
                    if (obj1[i] !== obj2[i]) {
                        return false;
                    }
                    continue;
                }
                // it's not a self reference so we are here
                if (!deepEquals(obj1[i], obj2[i], parents1, parents2)) {
                    return false;
                }
            } else {
                // obj2[i] does not exist
                return false;
            }
        }
    }
    return true;
};

测试:

// message is displayed on failure
// clean console === all tests passed
function assertTrue(cond, msg) {
    if (!cond) {
        console.log(msg);
    }
}

var a = 'sdf',
    b = 'sdf';
assertTrue(deepEquals(b, a), 'Strings are equal.');
b = 'dfs';
assertTrue(!deepEquals(b, a), 'Strings are not equal.');
a = 9;
b = 9;
assertTrue(deepEquals(b, a), 'Numbers are equal.');
b = 3;
assertTrue(!deepEquals(b, a), 'Numbers are not equal.');
a = false;
b = false;
assertTrue(deepEquals(b, a), 'Booleans are equal.');
b = true;
assertTrue(!deepEquals(b, a), 'Booleans are not equal.');
a = null;
assertTrue(!deepEquals(b, a), 'Boolean is not equal to null.');
a = function () {
    return true;
};
assertTrue(deepEquals(
[
    [1, 1, 1],
    [2, 'asdf', [1, a]],
    [3, {
        'a': 1.0
    },
    true]
], 
[
    [1, 1, 1],
    [2, 'asdf', [1, a]],
    [3, {
        'a': 1.0
    },
    true]
]), 'Arrays are equal.');
assertTrue(!deepEquals(
[
    [1, 1, 1],
    [2, 'asdf', [1, a]],
    [3, {
        'a': 1.0
    },
    true]
],
[
    [1, 1, 1],
    [2, 'asdf', [1, a]],
    [3, {
        'a': '1'
    },
    true]
]), 'Arrays are not equal.');
a = {
    prop: 'val'
};
a.self = a;
b = {
    prop: 'val'
};
b.self = a;
assertTrue(deepEquals(b, a), 'Immediate self referencing objects are equal.');
a.prop = 'shmal';
assertTrue(!deepEquals(b, a), 'Immediate self referencing objects are not equal.');
a = {
    prop: 'val',
    inside: {}
};
a.inside.self = a;
b = {
    prop: 'val',
    inside: {}
};
b.inside.self = a;
assertTrue(deepEquals(b, a), 'Deep self referencing objects are equal.');
b.inside.self = b;
assertTrue(!deepEquals(b, a), 'Deep self referencing objects are not equeal. Not the same instance.');
b.inside.self = {foo: 'bar'};
assertTrue(!deepEquals(b, a), 'Deep self referencing objects are not equal. Completely different object.');
a = {};
b = {};
a.self = a;
b.self = {};
assertTrue(!deepEquals(b, a), 'Empty object and self reference of an empty object.');

其他回答

如果您正在使用lodash,并且不想修改任何一个数组,则可以使用_.xor()函数。它将两个数组作为集合进行比较,并返回包含它们之差的集合。如果此差值的长度为零,则两个数组本质上相等:

var a = [1, 2, 3];
var b = [3, 2, 1];
var c = new Array(1, 2, 3);
_.xor(a, b).length === 0
true
_.xor(b, c).length === 0
true

即使这看起来超级简单,但有时它真的很有用。如果你所需要的只是看看两个数组是否有相同的项,并且它们的顺序相同,试试这个:

[1, 2, 3].toString() == [1, 2, 3].toString()
true
[1, 2, 3,].toString() == [1, 2, 3].toString()
true
[1,2,3].toString() == [1, 2, 3].toString()
true

然而,这并不适用于模式高级情况,如:

[[1,2],[3]].toString() == [[1],[2,3]].toString()
true

这取决于你需要什么。

对于数字和字符串等原始值,这是一个简单的解决方案:

a = [1,2,3]

b = [3,2,1]

a.sort().toString() == b.sort().toString() 

调用sort()将确保元素的顺序无关紧要。toString()调用将创建一个值以逗号分隔的字符串,以便可以测试两个字符串是否相等。

如果您希望检查对象数组的相等性和顺序并不重要,即。

areEqual ([{id:“0”},{id: " 1 "}], [{id: " 1 "}, {id: " 0 "})) / /真实的

首先要对数组进行排序。lodash有你需要的所有工具,通过组合sortBy和isEqual:

// arr1 & arr2: Arrays of objects 
// sortProperty: the property of the object with which you want to sort
// Note: ensure every object in both arrays has your chosen sortProperty
// For example, arr1 = [{id: "v-test_id0"}, {id: "v-test_id1"}]
// and          arr2 = [{id: "v-test_id1"}, {id: "v-test_id0"}]
// sortProperty should be 'id'

function areEqual (arr1, arr2, sortProperty) {
  return _.areEqual(_.sortBy(arr1, sortProperty), _.sortBy(arr2, sortProperty))
}

编辑:由于sortBy返回一个新数组,在排序之前不需要克隆数组。原始数组不会被改变。

注意,对于lodash的isEqual,顺序很重要。如果sortBy没有首先应用于每个数组,上面的例子将返回false。

var a= [1, 2, 3, '3'];
var b = [1, 2, 3];

var c = a.filter(function (i) { return ! ~b.indexOf(i); });

alert(c.length);