Range

This adds a simple way to get slices of an array using a Rust-like syntax in a function. Most use cases should not prefer to use this over the built-in Array.prototype.slice method, this is just a fancy wrapper around that. But this still does come in handy for some situations and is very flexable.

Usage

Simply add range as a dependancy and use the exportend range function:

// don't forget to add a version when you use it
import { range } from "https://deno.land/x/range";

// a quick array for the example
const arr = [1, 2, "hello", "world"];
// getting values from index 1 to 2
range("1..3")(arr); // [ 2, "hello" ]

Example

You can run the example.ts either by cloning the repo and running deno run example.ts or by running deno run https://deno.land/x/range/example.ts. The output should resemble something like what you see below:

arr: [ 1, 2, "hello", "world" ]

..: [ 1, 2, "hello", "world" ]
..=: [ 1, 2, "hello", "world" ]

1..3: [ 2, "hello" ]
1..=3: [ 2, "hello", "world" ]
..3: [ 1, 2, "hello" ]
..=3: [ 1, 2, "hello", "world" ]
1..: [ 2, "hello", "world" ]
1..=: [ 2, "hello", "world" ]

Tests

This module is fully tested by the the tests found in test.ts. Both errors and successes are tested to make sure that the module doesn’t regress. If you do change anything, make sure that the tests pass and are modified as needed, thanks.

Range vs Native

As said at the top:

“Most use cases should not prefer to use this over the built-in Array.prototype.slice method, this is just a fancy wrapper around that.”

Let’s see how you’d implement the same thing using both methods:

// native
arr.slice(1, 3);
// ranges
range("1..3")(arr);

As you can see, the native method is not only shorter, but faster too (based on the worst case I got running the benchmark):

benchmark native...
  10000 runs avg: 0.0012ms
benchmark range...
  10000 runs avg: 0.0032ms

If you want to run the benchmark yourself, you can either clone the repo and run deno run bench.ts or run deno run https://deno.land/x/range/bench.ts.