cartesian-mutable

Cartesian product with a twist: each set can mutate depending on the values picked from the previous sets.

Basic usage

The API is backwards compatible with many other cartesian modules on npm.

const cartesian = require('cartesian-mutable');
console.log(cartesian({
    greeting: ['Hello', 'Good bye'],
    name: ['Mr. Anderson', 'Agent Smith']
}));

🡇

[ { greeting: 'Hello', name: 'Mr. Anderson' },
  { greeting: 'Hello', name: 'Agent Smith' },
  { greeting: 'Good bye', name: 'Mr. Anderson' },
  { greeting: 'Good bye', name: 'Agent Smith' } ]

Fun stuff, that makes this module different

If you need a property to depend on other properties' values, use a function instead of an array. The function will be called with a single argument: an object containing values for all the properties above this one.

Mutate a set of values for a property

If the function returns an array, it will be used as a set of values for the property.

const cartesian = require('cartesian-mutable');
console.log(cartesian({
    meal: ['breakfast', 'lunch'],
    drink: (v) => v.meal === 'breakfast' ? ['water', 'milk'] : ['tea', 'coffee']
}));

🡇

[ { meal: 'breakfast', drink: 'water' },
  { meal: 'breakfast', drink: 'milk' },
  { meal: 'lunch', drink: 'tea' },
  { meal: 'lunch', drink: 'coffee' } ]

Make a property conditional

If the function returns an undefined, the property will not be used in the product.

const cartesian = require('cartesian-mutable');
console.log(cartesian({
    meal: ['breakfast', 'lunch'],
    drink: (v) => v.meal === 'breakfast' ? ['water', 'milk'] : ['tea', 'coffee'],
    sugar: (v) => v.meal === 'breakfast' ? undefined : [true, false] 
}));

🡇

[ { meal: 'breakfast', drink: 'water' },
  { meal: 'breakfast', drink: 'milk' },
  { meal: 'lunch', drink: 'tea', sugar: true },
  { meal: 'lunch', drink: 'tea', sugar: false },
  { meal: 'lunch', drink: 'coffee', sugar: true },
  { meal: 'lunch', drink: 'coffee', sugar: false } ]

Specify an explicit value for a property

If the function returns any other value (i.e. neither an Array nor an undefined) it will be used as a value for the property.

const cartesian = require('cartesian-mutable');
console.log(cartesian({
    meal: ['breakfast', 'lunch'],
    drink: (v) => v.meal === 'breakfast' ? ['water', 'milk'] : ['tea', 'coffee'],
    food: (v) => v.meal === 'breakfast' ? 'granola' : 'sandwich'
}));

🡇

[ { meal: 'breakfast', drink: 'water', food: 'granola' },
  { meal: 'breakfast', drink: 'milk', food: 'granola' },
  { meal: 'lunch', drink: 'tea', food: 'sandwich' },
  { meal: 'lunch', drink: 'coffee', food: 'sandwich' } ]

License

MIT License