【初心者向け】JavaScriptの配列と連想配列の違いとは？

What is meant by the subscript of an array? - Computer Applications | Shaalaa.com

Create a SafeArray class so that the user can specify both the upper and the lower bound of the array. Have the overloaded subscript operator check the index each time the array is accessed to ensure that it is not out of bounds. You'll need to add a two-argument constructor that specifies the upper and lower bounds.