🔸element index

JS ⟩ object ⟩ built-in ⟩ Array ⟩ element ⟩ index

(String)

array elements are numbered, starting from 0, this number is called the element's index, an index must be non-negtive integers❗

🧨 雷區

element index is string❗️

⭐️ 重點

JavaScript arrays are zero-based and use 32-bit indexes: the index of the first element is 0, and the highest possible index is 4294967294 (2³²−2).

JavaScript arrays have no notion of an “out of bounds” error. When you try to query a nonexistent property of any object, you don’t get an error; you simply get undefined.

👥 相關

• ✅ element index is accessed throught bracket notation [].

📘 手冊

• Guides ⟩ Arrays ⟩ Accessing and modifying array items ⭐️