比较详情


  • NaN 外,原始值使用 == 运算符进行比较。 如果双方都是 NaN,则视为相同。
  • 对象的类型标签应该是一样的。
  • 仅考虑自有属性
  • Error 名称和消息总是被比较,即使它们不是可枚举的属性。
  • 对象封装器作为对象和未封装的值进行比较。
  • Object 属性是无序比较的。
  • Map 键和 Set 项是无序比较的。
  • 当双方不同或双方遇到循环引用时,则递归停止。
  • 实现不测试对象的 [[Prototype]]
  • 不比较 Symbol 属性。
  • WeakMapWeakSet 的比较不依赖于它们的值。
  • RegExp 的 lastIndex、flags 和 source 总是被比较,即使它们不是可枚举的属性。

以下示例不会抛出 AssertionError,因为使用 == 运算符比较原始值。

import assert from 'node:assert';
// 注意:这不会抛出 AssertionError!

assert.deepEqual('+00000000', false);const assert = require('node:assert');
// 注意:这不会抛出 AssertionError!

assert.deepEqual('+00000000', false);

“深度”相等意味着子对象的可枚举"自有"属性也被评估:

import assert from 'node:assert';

const obj1 = {
  a: {
    b: 1,
  },
};
const obj2 = {
  a: {
    b: 2,
  },
};
const obj3 = {
  a: {
    b: 1,
  },
};
const obj4 = Object.create(obj1);

assert.deepEqual(obj1, obj1);
// OK

// b 的值不同:
assert.deepEqual(obj1, obj2);
// AssertionError: { a: { b: 1 } } deepEqual { a: { b: 2 } }

assert.deepEqual(obj1, obj3);
// OK

// 原型被忽略:
assert.deepEqual(obj1, obj4);
// AssertionError: { a: { b: 1 } } deepEqual {}const assert = require('node:assert');

const obj1 = {
  a: {
    b: 1,
  },
};
const obj2 = {
  a: {
    b: 2,
  },
};
const obj3 = {
  a: {
    b: 1,
  },
};
const obj4 = Object.create(obj1);

assert.deepEqual(obj1, obj1);
// OK

// b 的值不同:
assert.deepEqual(obj1, obj2);
// AssertionError: { a: { b: 1 } } deepEqual { a: { b: 2 } }

assert.deepEqual(obj1, obj3);
// OK

// 原型被忽略:
assert.deepEqual(obj1, obj4);
// AssertionError: { a: { b: 1 } } deepEqual {}

如果值不相等,则抛出 AssertionError,其 message 属性设置为等于 message 参数的值。 如果未定义 message 参数,则分配默认错误消息。 如果 message 参数是 Error 的实例,则将抛出错误而不是 AssertionError

  • Primitive values are compared with the == operator, with the exception of NaN. It is treated as being identical in case both sides are NaN.
  • Type tags of objects should be the same.
  • Only enumerable "own" properties are considered.
  • Error names and messages are always compared, even if these are not enumerable properties.
  • Object wrappers are compared both as objects and unwrapped values.
  • Object properties are compared unordered.
  • Map keys and Set items are compared unordered.
  • Recursion stops when both sides differ or both sides encounter a circular reference.
  • Implementation does not test the [[Prototype]] of objects.
  • Symbol properties are not compared.
  • WeakMap and WeakSet comparison does not rely on their values.
  • RegExp lastIndex, flags, and source are always compared, even if these are not enumerable properties.

The following example does not throw an AssertionError because the primitives are compared using the == operator.

import assert from 'node:assert';
// WARNING: This does not throw an AssertionError!

assert.deepEqual('+00000000', false);const assert = require('node:assert');
// WARNING: This does not throw an AssertionError!

assert.deepEqual('+00000000', false);

"Deep" equality means that the enumerable "own" properties of child objects are evaluated also:

import assert from 'node:assert';

const obj1 = {
  a: {
    b: 1,
  },
};
const obj2 = {
  a: {
    b: 2,
  },
};
const obj3 = {
  a: {
    b: 1,
  },
};
const obj4 = Object.create(obj1);

assert.deepEqual(obj1, obj1);
// OK

// Values of b are different:
assert.deepEqual(obj1, obj2);
// AssertionError: { a: { b: 1 } } deepEqual { a: { b: 2 } }

assert.deepEqual(obj1, obj3);
// OK

// Prototypes are ignored:
assert.deepEqual(obj1, obj4);
// AssertionError: { a: { b: 1 } } deepEqual {}const assert = require('node:assert');

const obj1 = {
  a: {
    b: 1,
  },
};
const obj2 = {
  a: {
    b: 2,
  },
};
const obj3 = {
  a: {
    b: 1,
  },
};
const obj4 = Object.create(obj1);

assert.deepEqual(obj1, obj1);
// OK

// Values of b are different:
assert.deepEqual(obj1, obj2);
// AssertionError: { a: { b: 1 } } deepEqual { a: { b: 2 } }

assert.deepEqual(obj1, obj3);
// OK

// Prototypes are ignored:
assert.deepEqual(obj1, obj4);
// AssertionError: { a: { b: 1 } } deepEqual {}

If the values are not equal, an AssertionError is thrown with a message property set equal to the value of the message parameter. If the message parameter is undefined, a default error message is assigned. If the message parameter is an instance of an Error then it will be thrown instead of the AssertionError.