array-cursor

Array cursor

Data structure that wraps an array. It allows to slice it without mutate the array itself. It just takes into consideration two indexes (begin and end).

Example:

var a = new ArrayCursor([1, 2, 3, 4]);
var b = a.slice(1, -1);

a.length; // 2
a.get(0); // 1
a.get(1); // 2
a.get(3); // 3
a.get(4); // 4

b.length; // 2
b.get(0); // 2
b.get(1); // 3

a.toArray(); // [1, 2, 3, 4] this creates a new array!
b.toArray(); // [2, 3] this creates a new array!

The API is quite limited but, if you don't need to mutate the array and you only need to see different slices, it is crazy fast! (try running npm run benchmarks).

API

You create an ArrayCursor with:

var arrayCursor = new ArrayCursor(array, begin, end);

begin and end follow the same rules as Array.prototype.slice.

Attributes

The length of the array is in the length attribute. Then original array is in data but you can only see from begin to end.

Methods

The object has the following methods:

• get(n) : return the n item
• slice(begin, end): return a new instance of ArrayCursor sliced in a different way (same API as Array.prototype.slice)
• forEach(cb): it is equivalent to Array.prototype.forEach
• toArray(): it returns a new array that is the slice of the array contained in this.data.
• It also support various array methods: map, filter, reduce

Why not using a proxy to access data seamlessly ?

As of node 8.7 proxies are so slow to instantiate that defeat completely the purpose of the library.