javascript - Object.is(x,y) 是否比其他比较更快？

Question

所以在 JavaScript 中我们有三个相等比较运算符。我一直在阅读 ECMAScript 规范并了解它们的工作原理。有件事打动了我。 Object.is() 内置函数的比较步骤更少，并且比其他运算符更有可能提前终止。那么这是否会使 Object.is() 比其他运算符运行得更快？

以下是规范片段:

Object.is()

1. If Type(x) is different from Type(y), return false.

2. If Type(x) is Number, then

   a. If x is NaN and y is NaN, return true.

   b. If x is +0 and y is -0, return false.

   c. If x is -0 and y is +0, return false.

   d. If x is the same Number value as y, return true.

   e. Return false.

3. Return SameValueNonNumber(x, y).

松散等于==

The comparison x == y, where x and y are values, produces true or false. Such a comparison is performed as follows:

1. If Type(x) is the same as Type(y), then

   a. Return the result of performing Strict Equality Comparison x === y.

2. If x is null and y is undefined, return true.
3. If x is undefined and y is null, return true.
4. If Type(x) is Number and Type(y) is String, return the result of the comparison x == ! ToNumber(y).
5. If Type(x) is String and Type(y) is Number, return the result of the comparison ! ToNumber(x) == y.
6. If Type(x) is Boolean, return the result of the comparison ! ToNumber(x) == y.
7. If Type(y) is Boolean, return the result of the comparison x == ! ToNumber(y).
8. If Type(x) is either String, Number, or Symbol and Type(y) is Object, return the result of the comparison x == ToPrimitive(y).
9. If Type(x) is Object and Type(y) is either String, Number, or Symbol, return the result of the comparison ToPrimitive(x) == y.
10. Return false.

严格等于===

The comparison x === y, where x and y are values, produces true or false. Such a comparison is performed as follows:

1. If Type(x) is different from Type(y), return false.

2. If Type(x) is Number, then

   a. If x is NaN, return false.

   b. If y is NaN, return false.

   c. If x is the same Number value as y, return true.

   d. If x is +0 and y is -0, return true.

   e. If x is -0 and y is +0, return true.

   f. Return false.

3. Return SameValueNonNumber(x, y).

如果从事 JavaScript 编译器工作的人可以回答这个问题，那就太好了!

Answer 1

规范中的步骤越少并不一定意味着实现中的步骤越少。各种优化都适用于此。所以最后，我们所能做的就是实际 race the horses! (在您的现实世界用例中，一些合成 while(true) Object.is(1, 1); 不会生成任何有用的结果)。如果它真的(特别是)更快，它是否会使您的代码更好，例如是

      Object.is(user.age, 3)

比

更清楚

      user.age === 3

?