比较详情

🌐 Comparison details

  • 原始值使用 Object.is() 进行比较。
  • 对象的类型标签应该相同。
  • 对象的 [[Prototype]] 是使用 === 运算符 进行比较的。
  • 只有可枚举的"自有"属性被考虑。
  • <Error> 名称、消息、原因和错误总是会被比较,即使它们不是可枚举属性。errors 也会被比较。
  • 可枚举的自身 Symbol 属性也会被比较。
  • 对象封装器 既作为对象也作为未拆封的值进行比较。
  • Object 属性是无序比较的。
  • <Map> 键和 <Set> 项目是无序比较的。
  • 当两边不同时或任一边遇到循环引用时,递归停止。
  • WeakMap、WeakSet 和 <Promise> 实例不会进行结构上的比较。它们只有在引用同一个对象时才相等。任何不同的 WeakMap、WeakSet 或 Promise 实例之间的比较都会导致不相等,即使它们包含相同的内容。
  • <RegExp> lastIndex、flags 和 source 总是会被比较,即使它们不是可枚举属性。
import assert from 'node:assert/strict';
// This fails because 1 !== '1'.
assert.deepStrictEqual({ a: 1 }, { a: '1' });
// AssertionError: Expected inputs to be strictly deep-equal:
// + actual - expected
//
// {
// + a: 1
// - a: '1'
// }
// The following objects don't have own properties
const date = new Date();
const object = {};
const fakeDate = {};
Object.setPrototypeOf(fakeDate, Date.prototype);
// Different [[Prototype]]:
assert.deepStrictEqual(object, fakeDate);
// AssertionError: Expected inputs to be strictly deep-equal:
// + actual - expected
//
// + {}
// - Date {}
// Different type tags:
assert.deepStrictEqual(date, fakeDate);
// AssertionError: Expected inputs to be strictly deep-equal:
// + actual - expected
//
// + 2018年04月26日T00:49:08.604Z
// - Date {}
assert.deepStrictEqual(NaN, NaN);
// OK because Object.is(NaN, NaN) is true.
// Different unwrapped numbers:
assert.deepStrictEqual(new Number(1), new Number(2));
// AssertionError: Expected inputs to be strictly deep-equal:
// + actual - expected
//
// + [Number: 1]
// - [Number: 2]
assert.deepStrictEqual(new String('foo'), Object('foo'));
// OK because the object and the string are identical when unwrapped.
assert.deepStrictEqual(-0, -0);
// OK
// Different zeros:
assert.deepStrictEqual(0, -0);
// AssertionError: Expected inputs to be strictly deep-equal:
// + actual - expected
//
// + 0
// - -0
const symbol1 = Symbol();
const symbol2 = Symbol();
assert.deepStrictEqual({ [symbol1]: 1 }, { [symbol1]: 1 });
// OK, because it is the same symbol on both objects.
assert.deepStrictEqual({ [symbol1]: 1 }, { [symbol2]: 1 });
// AssertionError [ERR_ASSERTION]: Inputs identical but not reference equal:
//
// {
// Symbol(): 1
// }
const weakMap1 = new WeakMap();
const weakMap2 = new WeakMap();
const obj = {};
weakMap1.set(obj, 'value');
weakMap2.set(obj, 'value');
// Comparing different instances fails, even with same contents
assert.deepStrictEqual(weakMap1, weakMap2);
// AssertionError: Values have same structure but are not reference-equal:
//
// WeakMap {
// <items unknown>
// }
// Comparing the same instance to itself succeeds
assert.deepStrictEqual(weakMap1, weakMap1);
// OK
const weakSet1 = new WeakSet();
const weakSet2 = new WeakSet();
weakSet1.add(obj);
weakSet2.add(obj);
// Comparing different instances fails, even with same contents
assert.deepStrictEqual(weakSet1, weakSet2);
// AssertionError: Values have same structure but are not reference-equal:
// + actual - expected
//
// WeakSet {
// <items unknown>
// }
// Comparing the same instance to itself succeeds
assert.deepStrictEqual(weakSet1, weakSet1);
// OKconst assert = require('node:assert/strict');
// This fails because 1 !== '1'.
assert.deepStrictEqual({ a: 1 }, { a: '1' });
// AssertionError: Expected inputs to be strictly deep-equal:
// + actual - expected
//
// {
// + a: 1
// - a: '1'
// }
// The following objects don't have own properties
const date = new Date();
const object = {};
const fakeDate = {};
Object.setPrototypeOf(fakeDate, Date.prototype);
// Different [[Prototype]]:
assert.deepStrictEqual(object, fakeDate);
// AssertionError: Expected inputs to be strictly deep-equal:
// + actual - expected
//
// + {}
// - Date {}
// Different type tags:
assert.deepStrictEqual(date, fakeDate);
// AssertionError: Expected inputs to be strictly deep-equal:
// + actual - expected
//
// + 2018年04月26日T00:49:08.604Z
// - Date {}
assert.deepStrictEqual(NaN, NaN);
// OK because Object.is(NaN, NaN) is true.
// Different unwrapped numbers:
assert.deepStrictEqual(new Number(1), new Number(2));
// AssertionError: Expected inputs to be strictly deep-equal:
// + actual - expected
//
// + [Number: 1]
// - [Number: 2]
assert.deepStrictEqual(new String('foo'), Object('foo'));
// OK because the object and the string are identical when unwrapped.
assert.deepStrictEqual(-0, -0);
// OK
// Different zeros:
assert.deepStrictEqual(0, -0);
// AssertionError: Expected inputs to be strictly deep-equal:
// + actual - expected
//
// + 0
// - -0
const symbol1 = Symbol();
const symbol2 = Symbol();
assert.deepStrictEqual({ [symbol1]: 1 }, { [symbol1]: 1 });
// OK, because it is the same symbol on both objects.
assert.deepStrictEqual({ [symbol1]: 1 }, { [symbol2]: 1 });
// AssertionError [ERR_ASSERTION]: Inputs identical but not reference equal:
//
// {
// Symbol(): 1
// }
const weakMap1 = new WeakMap();
const weakMap2 = new WeakMap();
const obj = {};
weakMap1.set(obj, 'value');
weakMap2.set(obj, 'value');
// Comparing different instances fails, even with same contents
assert.deepStrictEqual(weakMap1, weakMap2);
// AssertionError: Values have same structure but are not reference-equal:
//
// WeakMap {
// <items unknown>
// }
// Comparing the same instance to itself succeeds
assert.deepStrictEqual(weakMap1, weakMap1);
// OK
const weakSet1 = new WeakSet();
const weakSet2 = new WeakSet();
weakSet1.add(obj);
weakSet2.add(obj);
// Comparing different instances fails, even with same contents
assert.deepStrictEqual(weakSet1, weakSet2);
// AssertionError: Values have same structure but are not reference-equal:
// + actual - expected
//
// WeakSet {
// <items unknown>
// }
// Comparing the same instance to itself succeeds
assert.deepStrictEqual(weakSet1, weakSet1);
// OK

如果值不相等,将抛出一个 AssertionError,其 message 属性设置为 message 参数的值。如果 message 参数未定义,则会分配默认的错误消息。如果 message 参数是 <Error> 的实例,则将抛出该实例,而不是 AssertionError。

🌐 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 <Error> then it will be thrown instead of the AssertionError.

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