js-iterators

Ruby range iterators in JavaScript using syntax hacks

Usage no npm install needed!

<script type="module">
  import jsIterators from 'https://cdn.skypack.dev/js-iterators';
</script>

README

js-iterators (zero dependencies)

Ruby style iterators in JS. Ruby style ranges in JS


[...1.._10];              // [1, 2, 3, 4, 5, 6, 7, 8, 9]
[...1.._-10];             // [1, 0, -1, -2, ..., -9]
[...Math.PI._9];          // [3.141592653589793, 4.141592653589793, 5.141592653589793, 6.141592653589793, 7.141592653589793, 8.141592653589793]
[...(-1e3)._1e3];         // [-1000, -999, ..., 998, 999]
[...1e3._2e3];            // [1000, 1001, ..., 1999]
[...1..$10];              // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
[...1..__1_213e3];        // [1, 0, -1, ..., -1213]
[...1..__1_213e_3];       // [1, 0]

for( let i of 1.._10 ) {
  console.log(i+1);       // 2, 3, 4, ..., 10
}

Array.from(1..$10);       // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

[...(-10)._$10];          // [-10, -9, ..., 9, 10]
[...4..times];            // [0, 1, 2, 3]
[...5..upto(10)];          // [5, 6, 7, 8, 9, 10]
[...10..downto(5)];        // [10, 9, 8, 7, 6, 5]
[...4..step(10,2)];        // [4, 6, 8, 10]

get

$ npm i --save js-iterators@latest

contribute

PRs only thanks! :)

why not just use Ruby?

I'm on web

why not use this other library?

Syntax

why this?

Cool

Guide

  • <left_part><1 or 2 dots><right_part>

  • Left part must be a Number

  • Right part must start with _ or $ then be followed by a number

  • Negative numbers on left wrap in ()

  • Negative numbers on right prefix with extra _

  • Right-closed (inclusive end, e.g., [1,3] === 1, 2, 3) intervals use $

  • Right-open (non-inclusive end, e.g., [1,3) === 1, 2) intervals use _

  • Only 1 dot separating left and right parts when left part is:

    • a negative number (which must be wrapped in ( and )), e.g. Array.from((-10)._20)
    • a floating point number with decimal places, e.g. [...3.1415._10]
    • a variable, e.g. [...Math.PI._10]
    • an octal, e.g. [...0701._500]
    • a binary, e.g. [...0b101011._500]
    • a hexadecimal, e.g. [...0xfa._500]
    • a scientific-notation, e.g. [...1e3._1010]

  • Otherwise, two dots separating left and right parts

  • Ruby API

    • <range>.to_a send range to an array, e.g. 1.._10.to_a
    • <number>.upto(high) count up from number to high inclusive by 1s (or -1s)
    • <number>.downto(low) count down from number to low inclusive by 1s (or -1s)
    • <number>.step(to, by) count from number to to inclusive by bys (or -bys)
    • <number>.times iterate number times (and return integers 0..number-1)
    • Ruby API is based on Ruby range and Ruby number iterators