difference between n and n.length javascript code example

Example 1: create range array javascript

[...Array(10).keys()]
//=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Example 2: list from 1 to 100 js

[...Array(100).keys()]
//=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]