JavaScript中的对象比较
在JavaScript中比较对象的最佳方法是什么 例如:JavaScript中的对象比较,javascript,object,comparison,object-comparison,Javascript,Object,Comparison,Object Comparison,在JavaScript中比较对象的最佳方法是什么 例如: var user1 = {name : "nerd", org: "dev"}; var user2 = {name : "nerd", org: "dev"}; var eq = user1 == user2; alert(eq); // gives false 我知道如果两个对象引用的是完全相同的对象,那么它们是相等的,但是有没有办法检查它们是否具有相同的属性值 以下方法对我有效,但这是唯一的可能性吗 var eq = Object
var user1 = {name : "nerd", org: "dev"};
var user2 = {name : "nerd", org: "dev"};
var eq = user1 == user2;
alert(eq); // gives false
我知道如果两个对象引用的是完全相同的对象,那么它们是相等的,但是有没有办法检查它们是否具有相同的属性值
以下方法对我有效,但这是唯一的可能性吗
var eq = Object.toJSON(user1) == Object.toJSON(user2);
alert(eq); // gives true
当然,这不是唯一的方法——您可以原型化一个方法(这里是针对对象的,但我当然不建议对实时代码使用对象)来复制C#/Java风格的比较方法 编辑,因为似乎需要一个通用示例:
Object.prototype.equals = function(x)
{
for(p in this)
{
switch(typeof(this[p]))
{
case 'object':
if (!this[p].equals(x[p])) { return false }; break;
case 'function':
if (typeof(x[p])=='undefined' || (p != 'equals' && this[p].toString() != x[p].toString())) { return false; }; break;
default:
if (this[p] != x[p]) { return false; }
}
}
for(p in x)
{
if(typeof(this[p])=='undefined') {return false;}
}
return true;
}
请注意,使用toString()测试方法绝对不够好,但是一个可以接受的方法非常困难,因为空格是否有意义的问题,更不用说同义词方法和使用不同实现产生相同结果的方法了。一般来说,针对对象进行原型设计的问题。如果你想明确地检查方法,你可以使用method.toSource()或method.toString()方法。不幸的是,没有完美的方法,除非你递归地使用
\u proto\u
并访问所有不可枚举的属性,但这只适用于Firefox
所以我能做的就是猜测使用场景
1)快速且有限。 当您有简单的JSON样式的对象,但其中没有方法和DOM节点时,此选项有效:
JSON.stringify(obj1) === JSON.stringify(obj2)
属性的顺序很重要,因此对于以下对象,此方法将返回false:
x = {a: 1, b: 2};
y = {b: 2, a: 1};
2)速度慢且更通用。 在不深入原型的情况下比较对象,然后递归地比较属性的投影,还比较构造函数 这几乎是正确的算法:
function deepCompare () {
var i, l, leftChain, rightChain;
function compare2Objects (x, y) {
var p;
// remember that NaN === NaN returns false
// and isNaN(undefined) returns true
if (isNaN(x) && isNaN(y) && typeof x === 'number' && typeof y === 'number') {
return true;
}
// Compare primitives and functions.
// Check if both arguments link to the same object.
// Especially useful on the step where we compare prototypes
if (x === y) {
return true;
}
// Works in case when functions are created in constructor.
// Comparing dates is a common scenario. Another built-ins?
// We can even handle functions passed across iframes
if ((typeof x === 'function' && typeof y === 'function') ||
(x instanceof Date && y instanceof Date) ||
(x instanceof RegExp && y instanceof RegExp) ||
(x instanceof String && y instanceof String) ||
(x instanceof Number && y instanceof Number)) {
return x.toString() === y.toString();
}
// At last checking prototypes as good as we can
if (!(x instanceof Object && y instanceof Object)) {
return false;
}
if (x.isPrototypeOf(y) || y.isPrototypeOf(x)) {
return false;
}
if (x.constructor !== y.constructor) {
return false;
}
if (x.prototype !== y.prototype) {
return false;
}
// Check for infinitive linking loops
if (leftChain.indexOf(x) > -1 || rightChain.indexOf(y) > -1) {
return false;
}
// Quick checking of one object being a subset of another.
// todo: cache the structure of arguments[0] for performance
for (p in y) {
if (y.hasOwnProperty(p) !== x.hasOwnProperty(p)) {
return false;
}
else if (typeof y[p] !== typeof x[p]) {
return false;
}
}
for (p in x) {
if (y.hasOwnProperty(p) !== x.hasOwnProperty(p)) {
return false;
}
else if (typeof y[p] !== typeof x[p]) {
return false;
}
switch (typeof (x[p])) {
case 'object':
case 'function':
leftChain.push(x);
rightChain.push(y);
if (!compare2Objects (x[p], y[p])) {
return false;
}
leftChain.pop();
rightChain.pop();
break;
default:
if (x[p] !== y[p]) {
return false;
}
break;
}
}
return true;
}
if (arguments.length < 1) {
return true; //Die silently? Don't know how to handle such case, please help...
// throw "Need two or more arguments to compare";
}
for (i = 1, l = arguments.length; i < l; i++) {
leftChain = []; //Todo: this can be cached
rightChain = [];
if (!compare2Objects(arguments[0], arguments[i])) {
return false;
}
}
return true;
}
函数deepCompare(){
变量i、l、左链、右链;
函数compare2对象(x,y){
var-p;
//请记住,NaN===NaN返回false
//并且isNaN(未定义)返回true
如果(isNaN(x)&&isNaN(y)&&typeof x==='number'&&typeof y=='number'){
返回true;
}
//比较原语和函数。
//检查两个参数是否链接到同一个对象。
//在比较原型的步骤中特别有用
如果(x==y){
返回true;
}
//在构造函数中创建函数时工作。
//比较日期是一个常见的场景。另一个内置的?
//我们甚至可以处理通过iframe传递的函数
if((x的类型==='函数'&&y的类型==='函数')||
(x实例日期和y实例日期)||
(x RegExp实例和y RegExp实例)||
(x字符串实例和y字符串实例)||
(x实例编号和y实例编号)){
返回x.toString()==y.toString();
}
//最后,我们尽可能地检查原型
if(!(对象的x实例和对象的y实例)){
返回false;
}
if(x.isPrototypeOf(y)| | y.isPrototypeOf(x)){
返回false;
}
if(x.constructor!==y.constructor){
返回false;
}
如果(x.prototype!==y.prototype){
返回false;
}
//检查不定式链接循环
if(leftChain.indexOf(x)>-1 | | righchain.indexOf(y)>-1){
返回false;
}
//快速检查一个对象是另一个对象的子集。
//todo:缓存参数[0]的结构以提高性能
对于(p in y){
如果(y.hasOwnProperty(p)!==x.hasOwnProperty(p)){
返回false;
}
else if(y[p]的类型!==x[p]的类型){
返回false;
}
}
对于(x中的p){
如果(y.hasOwnProperty(p)!==x.hasOwnProperty(p)){
返回false;
}
else if(y[p]的类型!==x[p]的类型){
返回false;
}
开关(类型(x[p])){
案例“对象”:
案例“功能”:
左链推(x);
右链推(y);
if(!compare2Objects(x[p],y[p])){
返回false;
}
leftChain.pop();
rightshain.pop();
打破
违约:
如果(x[p]!==y[p]){
返回false;
}
打破
}
}
返回true;
}
if(arguments.length<1){
return true;//默默死去?不知道如何处理这种情况,请帮忙。。。
//抛出“需要两个或多个参数进行比较”;
}
对于(i=1,l=arguments.length;i
已知问题(嗯,它们的优先级很低,可能您永远不会注意到):
- 原型结构不同但投影相同的对象
- 函数可以有相同的文本,但引用不同的闭包
测试:通过测试。如果您在没有JSON库的情况下工作,这可能会帮助您:
Object.prototype.equals = function(b) {
var a = this;
for(i in a) {
if(typeof b[i] == 'undefined') {
return false;
}
if(typeof b[i] == 'object') {
if(!b[i].equals(a[i])) {
return false;
}
}
if(b[i] != a[i]) {
return false;
}
}
for(i in b) {
if(typeof a[i] == 'undefined') {
return false;
}
if(typeof a[i] == 'object') {
if(!a[i].equals(b[i])) {
return false;
}
}
if(a[i] != b[i]) {
return false;
}
}
return true;
}
var a = {foo:'bar', bar: {blub:'bla'}};
var b = {foo:'bar', bar: {blub:'blob'}};
alert(a.equals(b)); // alert's a false
我对上面的代码做了一些修改。对我来说0!==false和null!==未定义。如果不需要这样严格的检查,请在代码中删除一个“=”登录“this[p]!==x[p]”
Object.prototype.equals = function(x){
for (var p in this) {
if(typeof(this[p]) !== typeof(x[p])) return false;
if((this[p]===null) !== (x[p]===null)) return false;
switch (typeof(this[p])) {
case 'undefined':
if (typeof(x[p]) != 'undefined') return false;
break;
case 'object':
if(this[p]!==null && x[p]!==null && (this[p].constructor.toString() !== x[p].constructor.toString() || !this[p].equals(x[p]))) return false;
break;
case 'function':
if (p != 'equals' && this[p].toString() != x[p].toString()) return false;
break;
default:
if (this[p] !== x[p]) return false;
}
}
return true;
}
然后,我用以下对象对其进行了测试:
var a = {a: 'text', b:[0,1]};
var b = {a: 'text', b:[0,1]};
var c = {a: 'text', b: 0};
var d = {a: 'text', b: false};
var e = {a: 'text', b:[1,0]};
var f = {a: 'text', b:[1,0], f: function(){ this.f = this.b; }};
var g = {a: 'text', b:[1,0], f: function(){ this.f = this.b; }};
var h = {a: 'text', b:[1,0], f: function(){ this.a = this.b; }};
var i = {
a: 'text',
c: {
b: [1, 0],
f: function(){
this.a = this.b;
}
}
};
var j = {
a: 'text',
c: {
b: [1, 0],
f: function(){
this.a = this.b;
}
}
};
var k = {a: 'text', b: null};
var l = {a: 'text', b: undefined};
a==b预期为真;返回真值
a==c预期为假;返回错误
c==d预期为假;返回错误
a==e预期为假;返回错误
f==g预期为真;返回真值
h==g预期为假;返回错误
i==j预期为真;返回真值
d==k预期为假;返回错误
k==l预期为假;返回false我编写了这段代码用于对象比较,它似乎可以工作。检查断言:
function countProps(obj) {
var count = 0;
for (k in obj) {
if (obj.hasOwnProperty(k)) {
count++;
}
}
return count;
};
function objectEquals(v1, v2) {
if (typeof(v1) !== typeof(v2)) {
return false;
}
if (typeof(v1) === "function") {
return v1.toString() === v2.toString();
}
if (v1 instanceof Object && v2 instanceof Object) {
if (countProps(v1) !== countProps(v2)) {
return false;
}
var r = true;
for (k in v1) {
r = objectEquals(v1[k], v2[k]);
if (!r) {
return false;
}
}
return true;
} else {
return v1 === v2;
}
}
assert.isTrue(objectEquals(null,null));
assert.isFalse(objectEquals(null,undefined));
assert.isTrue(objectEquals("hi","hi"));
assert.isTrue(objectEquals(5,5));
assert.isFalse(objectEquals(5,10));
assert.isTrue(objectEquals([],[]));
assert.isTrue(objectEquals([1,2],[1,2]));
assert.isFalse(objectEquals([1,2],[2,1]));
assert.isFalse(objectEquals([1,2],[1,2,3]));
assert.isTrue(objectEquals({},{}));
assert.isTrue(objectEquals({a:1,b:2},{a:1,b:2}));
assert.isTrue(objectEquals({a:1,b:2},{b:2,a:1}));
assert.isFalse(objectEquals({a:1,b:2},{a:1,b:3}));
assert.isTrue(objectEquals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}},{1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}));
assert.isFalse(objectEquals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}},{1:{name:"mhc",age:28}, 2:{name:"arb",age:27}}));
assert.isTrue(objectEquals(function(x){return x;},function(x){return x;}));
assert.isFalse(objectEquals(function(x){return x;},function(y){return y+2;}));
这是我的版本,这个线程中的大部分内容都是集成的(测试用例的计数相同): 下面是我的测试用例:
assertFalse({}.equals(null));
assertFalse({}.equals(undefined));
assertTrue("String", "hi".equals("hi"));
assertTrue("Number", new Number(5).equals(5));
assertFalse("Number", new Number(5).equals(10));
assertFalse("Number+String", new Number(1).equals("1"));
assertTrue([].equals([]));
assertTrue([1,2].equals([1,2]));
assertFalse([1,2].equals([2,1]));
assertFalse([1,2].equals([1,2,3]));
assertTrue(new Date("2011-03-31").equals(new Date("2011-03-31")));
assertFalse(new Date("2011-03-31").equals(new Date("1970-01-01")));
assertTrue({}.equals({}));
assertTrue({a:1,b:2}.equals({a:1,b:2}));
assertTrue({a:1,b:2}.equals({b:2,a:1}));
assertFalse({a:1,b:2}.equals({a:1,b:3}));
assertTrue({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}.equals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}));
assertFalse({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}.equals({1:{name:"mhc",age:28}, 2:{name:"arb",age:27}}));
assertTrue("Function", (function(x){return x;}).equals(function(x){return x;}));
assertFalse("Function", (function(x){return x;}).equals(function(y){return y+2;}));
var a = {a: 'text', b:[0,1]};
var b = {a: 'text', b:[0,1]};
var c = {a: 'text', b: 0};
var d = {a: 'text', b: false};
var e = {a: 'text', b:[1,0]};
var f = {a: 'text', b:[1,0], f: function(){ this.f = this.b; }};
var g = {a: 'text', b:[1,0], f: function(){ this.f = this.b; }};
var h = {a: 'text', b:[1,0], f: function(){ this.a = this.b; }};
var i = {
a: 'text',
c: {
b: [1, 0],
f: function(){
this.a = this.b;
}
}
};
var j = {
a: 'text',
c: {
b: [1, 0],
f: function(){
this.a = this.b;
}
}
};
var k = {a: 'text', b: null};
var l = {a: 'text', b: undefined};
assertTrue(a.equals(b));
assertFalse(a.equals(c));
assertFalse(c.equals(d));
assertFalse(a.equals(e));
assertTrue(f.equals(g));
assertFalse(h.equals(g));
assertTrue(i.equals(j));
assertFalse(d.equals(k));
assertFalse(k.equals(l));
简单的
assertFalse({}.equals(null));
assertFalse({}.equals(undefined));
assertTrue("String", "hi".equals("hi"));
assertTrue("Number", new Number(5).equals(5));
assertFalse("Number", new Number(5).equals(10));
assertFalse("Number+String", new Number(1).equals("1"));
assertTrue([].equals([]));
assertTrue([1,2].equals([1,2]));
assertFalse([1,2].equals([2,1]));
assertFalse([1,2].equals([1,2,3]));
assertTrue(new Date("2011-03-31").equals(new Date("2011-03-31")));
assertFalse(new Date("2011-03-31").equals(new Date("1970-01-01")));
assertTrue({}.equals({}));
assertTrue({a:1,b:2}.equals({a:1,b:2}));
assertTrue({a:1,b:2}.equals({b:2,a:1}));
assertFalse({a:1,b:2}.equals({a:1,b:3}));
assertTrue({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}.equals({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}));
assertFalse({1:{name:"mhc",age:28}, 2:{name:"arb",age:26}}.equals({1:{name:"mhc",age:28}, 2:{name:"arb",age:27}}));
assertTrue("Function", (function(x){return x;}).equals(function(x){return x;}));
assertFalse("Function", (function(x){return x;}).equals(function(y){return y+2;}));
var a = {a: 'text', b:[0,1]};
var b = {a: 'text', b:[0,1]};
var c = {a: 'text', b: 0};
var d = {a: 'text', b: false};
var e = {a: 'text', b:[1,0]};
var f = {a: 'text', b:[1,0], f: function(){ this.f = this.b; }};
var g = {a: 'text', b:[1,0], f: function(){ this.f = this.b; }};
var h = {a: 'text', b:[1,0], f: function(){ this.a = this.b; }};
var i = {
a: 'text',
c: {
b: [1, 0],
f: function(){
this.a = this.b;
}
}
};
var j = {
a: 'text',
c: {
b: [1, 0],
f: function(){
this.a = this.b;
}
}
};
var k = {a: 'text', b: null};
var l = {a: 'text', b: undefined};
assertTrue(a.equals(b));
assertFalse(a.equals(c));
assertFalse(c.equals(d));
assertFalse(a.equals(e));
assertTrue(f.equals(g));
assertFalse(h.equals(g));
assertTrue(i.equals(j));
assertFalse(d.equals(k));
assertFalse(k.equals(l));
Utils.compareObjects = function(o1, o2){
for(var p in o1){
if(o1.hasOwnProperty(p)){
if(o1[p] !== o2[p]){
return false;
}
}
}
for(var p in o2){
if(o2.hasOwnProperty(p)){
if(o1[p] !== o2[p]){
return false;
}
}
}
return true;
};
function unwrapStringOrNumber(obj) {
return (obj instanceof Number || obj instanceof String
? obj.valueOf()
: obj);
}
function areEquivalent(a, b) {
a = unwrapStringOrNumber(a);
b = unwrapStringOrNumber(b);
if (a === b) return true; //e.g. a and b both null
if (a === null || b === null || typeof (a) !== typeof (b)) return false;
if (a instanceof Date)
return b instanceof Date && a.valueOf() === b.valueOf();
if (typeof (a) !== "object")
return a == b; //for boolean, number, string, xml
var newA = (a.areEquivalent_Eq_91_2_34 === undefined),
newB = (b.areEquivalent_Eq_91_2_34 === undefined);
try {
if (newA) a.areEquivalent_Eq_91_2_34 = [];
else if (a.areEquivalent_Eq_91_2_34.some(
function (other) { return other === b; })) return true;
if (newB) b.areEquivalent_Eq_91_2_34 = [];
else if (b.areEquivalent_Eq_91_2_34.some(
function (other) { return other === a; })) return true;
a.areEquivalent_Eq_91_2_34.push(b);
b.areEquivalent_Eq_91_2_34.push(a);
var tmp = {};
for (var prop in a)
if(prop != "areEquivalent_Eq_91_2_34")
tmp[prop] = null;
for (var prop in b)
if (prop != "areEquivalent_Eq_91_2_34")
tmp[prop] = null;
for (var prop in tmp)
if (!areEquivalent(a[prop], b[prop]))
return false;
return true;
} finally {
if (newA) delete a.areEquivalent_Eq_91_2_34;
if (newB) delete b.areEquivalent_Eq_91_2_34;
}
}
function object_equals( x, y ) {
if ( x === y ) return true;
// if both x and y are null or undefined and exactly the same
if ( ! ( x instanceof Object ) || ! ( y instanceof Object ) ) return false;
// if they are not strictly equal, they both need to be Objects
if ( x.constructor !== y.constructor ) return false;
// they must have the exact same prototype chain, the closest we can do is
// test there constructor.
for ( var p in x ) {
if ( ! x.hasOwnProperty( p ) ) continue;
// other properties were tested using x.constructor === y.constructor
if ( ! y.hasOwnProperty( p ) ) return false;
// allows to compare x[ p ] and y[ p ] when set to undefined
if ( x[ p ] === y[ p ] ) continue;
// if they have the same strict value or identity then they are equal
if ( typeof( x[ p ] ) !== "object" ) return false;
// Numbers, Strings, Functions, Booleans must be strictly equal
if ( ! object_equals( x[ p ], y[ p ] ) ) return false;
// Objects and Arrays must be tested recursively
}
for ( p in y )
if ( y.hasOwnProperty( p ) && ! x.hasOwnProperty( p ) )
return false;
// allows x[ p ] to be set to undefined
return true;
}