Joins values together. 📦 😺 🏃 📼 🌔 📜 📰 📘 Similar: concat, join. This is part of package extra-iterable. iterable.join(x, [sep]); // x: an iterable // sep: separator (,) const iterable = require("extra-iterable"); var x = [1, 2]; iterable.join(x); // "1,2" iterable.join(x, " : "); // "1 : 2" References Array.prototype.join: MDN web docs