关于 Number.MAX_VALUE [英] something about Number.MAX_VALUE

问题描述

在 Javascript 中，Number.MAX_VALUE 是数字的最大值.我有一个问题

In Javascript, Number.MAX_VALUE is the biggest value for a number. I got a question that

(Number.MAX_VALUE + 123) == Number.MAX_VALUE  //true
(Number.MAX_VALUE + Number.MAX_VALUE) == Number.MAX_VALUE  //false

我无法理解.有人可以解释一下吗?

I can't understand. Can someone explain me?

推荐答案

在第一个示例中，您只需增加一个非常小的数字:123 根据 1.79^308 什么都不是.所以你失去"了一些精度:它不会改变数字.

In the first example, you just increase your number by a really tiny number: 123 according to 1.79^308 is nothing. So you "lost" some precision: it does not change the number.

在第二个中，你超过了最大值，所以你的数字不再是数字，它是Infinity.

In the second one, you exceed the max value, so your number is not a number anymore, it is Infinity.

console.log(Number.MAX_VALUE + 123);
console.log(Number.MAX_VALUE + Number.MAX_VALUE);

/* Is (Number.MAX_VALUE + Number.MAX_VALUE) a number? */
console.log(Number.isInteger(Number.MAX_VALUE + Number.MAX_VALUE));

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