javascript - UnderscoreJS _.every 为空

Question

似乎 null 应该等于 null。那么为什么

_.every([null], _.identity);
false

_.any([null], _.identity);
false

这个结果更有意义(在我看来)

null === _.identity(null);
true

Answer 1

every 不做任何比较，它只是期望返回一个真值/假值。 null 是假的。来自内置 every 的 MDN:

The every method executes the provided callback function once for each element present in the array until it finds one where callback returns a falsy value (a value that becomes false when converted to a Boolean). If such an element is found, the every method immediately returns false. Otherwise, if callback returned a true value for all elements, every will return true.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/every