javascript - 为什么 JavaScript Sets/Maps 使用 `size` 而不是 `length` ？

Question

在查看 JavaScript 的新变化时，我注意到 Set和 Map使用 .size 而不是像数组那样的 .length。

这似乎是对数组正常情况的毫无意义的转移 - 只需要记住一件事。

这有什么好的设计理由吗？

Answer 1

esdiscuss 线程中有很多讨论 "Set length property" .这是一个激烈争论的问题，因此您不一定同意该决议也就不足为奇了。

esdiscuss 中对此有大量争论。最终，盛行的论点(ES2015 的集合具有 size 而不是 length 的事实证明)在 a post by David Bruant 中进行了总结。 :

...for me 'length' refers to a measurement with something like a ruler. You start at 0 and see up to where it goes. This is very accurate for an array which is an indexed set (starting at 0 and growing) and for arrays as considered in C (continuous sequence of bytes) which ECMAScript arrays seem inspired of. This is probably less relevant for unordered collections such as sets which I'd tend to consider as a messy bag.

并在 a post by Dean Landolt 中进一步讨论:

Just wanted to jump in and say non-writable length is consistent with String behavior as well, but David makes a good point about length implying metric topology. David's suggestion of count is nice. ISTM what we're talking about is cardinality, but no need to get too silly w/ precision. Though size is just fine with me, and has plenty of prior art.