[V8 Deep Dives] Understanding Array Internals

Photo by Antonio Garcia on UnsplashIn the previous part of this series, we were discussing Map and Set, standard collections introduced in ES6. This time we will focus on JavaScript arrays. Arrays, which are essentially list-like objects, are one of the core features of the language and every JavaScript developer has a solid experience in working with them. This blog post does not try to give you

[yuya_presto]

V8ではArrayがあるサイズより大きくなると、packedでもholeyでもないただのオブジェクト扱いになるらしい。ちなみにtompngさんいわく、でかい空の配列でfor ofすると、holeyは遅く、ただのオブジェクトは瞬殺だったとか。