const rangem = require('rangem');

const ranges = rangem.union([{ from: 1, to: 5 }, { from: 5, to: 10 }]);

// ➜ [{ from: 1, to: 10 }]

const range = ranges.pop(); // { from: 1, to: 3 }

rangem.subtract(range, [{ from: 5, to: 7 }]);

// ➜ [{ from: 1, to: 5 }, { from: 7, to: 10 }]

const union = require('rangem').union;

const ranges = [{ from: 1, to: 5 }, { from: 3, to: 6 }, { from: 10, to: 20 }];

union(ranges);

// ➜ [{ from: 1, to: 6 }, { from: 10, to: 20 }]

const subtract = require('rangem').subtract;

const fromRange = { from: 10, to: 20 };
const whatRanges = [{ from: 10, to: 12 }, { from: 15, to: 18 }]

subtract(fromRange, whatRanges);

// ➜ [{ from: 12, to: 15 }, { from: 18, to: 20 }]