ammo

HTTP Range processing utilities.

Usage

// basic usage
const range = Ammo.header('bytes=1-5', 10);
// range --> [{ from: 1, to: 5 }]

// multiple ranges
const range = Ammo.header('bytes=1-5,7-10', 10);
// range --> [{ from: 1, to: 5 }, { from: 7, to: 9 }]

// streams (get range within a `source`)
const range = Ammo.header('bytes=1000-4000', 5000);
const stream = new Ammo.Stream(range[0]);
const buffer = await Wreck.read(source.pipe(stream));

// buffer is the portion of source within range

API

header(header, length)

Parses the range from a HTTP header.

• header - A string in the form of bytes=from-to, where from and to are integers specifying the range. Both are optional. Multiple ranges can be passed as a comma delimited list.
• length - A positive integer specifying the maximum length the range can cover. If a to value passed in the header string is greater than length, the to value is set as length - 1.

Returns an array of objects with the properties from and to, which specify the beginning and ending of the range. Overlapping ranges are combined into one object. Returns null for invalid input.

new Ammo.Stream(range)

Creates a Transform Stream that extracts the portion of a piped in stream within range.

• range - an object with the properties from and to that specify the range of the piped in stream to read. Objects returned by Ammo.header can be passed into range.