javascript - 为什么 JavaScript 中的 "Infinity==Infinity"变为真？

Question

据我所知，在数学中 Infinity 和 NaN 都是模糊值。众所周知:

console.log(NaN == NaN); //-> false

同时

console.log(Infinity==Infinity); //-> true

我想知道为什么第二个代码的结果是true。我希望第二个的结果应该是 false，但事实并非如此。

你能帮帮我吗？我真的很感激。谢谢。

Answer 1

这就是为什么:

NaN compares unequal (via ==, !=, ===, and !==) to any other value -- including to another NaN value. Use Number.isNaN() or isNaN() to most clearly determine whether a value is NaN. Or perform a self-comparison: NaN, and only NaN, will compare unequal to itself.

来源:https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/NaN

The initial value of Infinity is Number.POSITIVE_INFINITY. The value Infinity (positive infinity) is greater than any other number. This value behaves mathematically like infinity; for example, any positive number multiplied by Infinity is Infinity, and anything divided by Infinity is 0.

来源:https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Infinity

您可能还对使用 Number 的 isFinite 方法感兴趣:

Number.isFinite(Infinity);  // false
Number.isFinite(NaN);       // false

阅读 Number.isFinite():https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isFinite