interval-op v0.2.0

interval-op

0-dependencies library implemeting basic operations on discrete intervals where boundary conditions reflect the intuitive expectations when dealing with availabilities.

// Union behaves like with closed intervals
[9 .. 12] U [12 .. 17] = [9 .. 17]

// Substraction behaves like with open intervals
[9 .. 17] - [15 .. 17] = [9 .. 15]

Install

npm install interval-op

Usage

• Intervals are represented as arrays of length 2
  • [start, end]
• The functions manipulate sets of intervals which are represented as arrays of intervals:

  • [ [start1, end1], [start2, end2], ... ]

Examples:

const { union, subtract } = require('interval-op')
console.log( union([ [9, 12], [12, 17] ]) )          // => [[9, 17]]
console.log( subtract([ [9, 17] ], [ [15, 17] ]) )   // => [[9, 15]]

More examples can be found in test/test.js

Assumptions

The library assumes that the elements used as interval boundaries all have an order relation and can be compared with the relational operators >, <, >= and <=.

For example, it can be used with numbers or dates.

To use it with a more complex object, you can read about Abstract Relational Comparison and Symbol.toPrimitive

See test/ComplexWithRelation.js for an example of custom class implementing Symbol.toPrimitive

Development

• Install dev dependencies with npm install the library has no production dependencies, but uses standardJS for linting/formatting
• Run the test suite npm run test
• Run the linter with npx standard --fix