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Range aka interval object. Supports exclusive and infinite ranges.


stRange.js is a range object for JavaScript. Use it to have a single value type with two endpoints and their boundaries. Also implements an interval tree for quick lookups. Stringifies itself in the style of [begin,end) and allows you to parse a string back. Also useful with PostgreSQL.

stRange.js follows semantic versioning, so feel free to depend on its major version with something like >= 1.0.0 < 2 (a.k.a ^1.0.0).

npm install strange

stRange.js doesn't yet have a build ready for the browser, but you might be able to use Browserify to have it run there till then.

Create a Range object by passing in a beginning and end:

var Range = require("strange")
var range = new Range(1, 5)

Check if something is a range and use it:

var Range = require("strange")
if (range instanceof Range) console.log(range.begin, range.end)

You can set a range's bounds by passing the bounds as a two-character string of parentheses as the 3rd argument:

new Range(1, 3, "[)")

Bounds signify whether the range includes or excludes that particular endpoint. The range above therefore includes numbers >= 1 < 3.

Pair Meaning
() open
[] closed
[) left-closed, right-open
(] left-open, right-closed

To parse a range stringified by Range.prototype.toString, pass it to Range.parse:

Range.parse("[a,z)") // => new Range("a", "z", "[)") 

To have stRange.js also parse the endpoints, pass a function to Range.parse:

Range.parse("[42,69]", Number) // => new Range(42, 69) 

The string format used by stRange.js matches PostgreSQL's range type format. You can therefore use stRange.js to parse and stringify ranges for your database.

For extended documentation on all functions, please see the stRange.js API Documentation.



stRange.js is released under a Lesser GNU Affero General Public License, which in summary means:

  • You can use this program for no cost.
  • You can use this program for both personal and commercial reasons.
  • You do not have to share your own program's code which uses this program.
  • You have to share modifications (e.g bug-fixes) you've made to this program.

For more convoluted language, see the LICENSE file.

Andri Möll typed this and the code.
Monday Calendar supported the engineering work.

If you find stRange.js needs improving, please don't hesitate to type to me now at or create an issue online.