flatMap

Flattens nested lists, using map function. 🏃 📼 📦 🌔 📒

Alternatives: flat, flatMap.

lists.flatMap(x, [fm], [ft]);
// x:  nested lists
// fm: map function (v, k, x)
// ft: test function (v, k, x)

const lists = require('extra-lists');

var x = [
  ['ab', [['a', 1], ['b', 2]]],
  ['cde', [['c', 3], ['de', [['d', 4], ['e', [['e', 5]]]]]]]
];
[...entries.flatMap(x)];
// [ [ 'a', 1 ], [ 'b', 2 ], [ 'c', 3 ], [ 'de', [ [Array], [Array] ] ] ]

[...entries.flatMap(x, v => entries.flat(v, 1))];
// [
//   [ 'a', 1 ],
//   [ 'b', 2 ],
//   [ 'c', 3 ],
//   [ 'd', 4 ],
//   [ 'e', [ [Array] ] ]
// ]

[...entries.flatMap(x, v => entries.flat(v))];
// [ [ 'a', 1 ], [ 'b', 2 ], [ 'c', 3 ], [ 'd', 4 ], [ 'e', 5 ] ]

references

• Array.prototype.flat: MDN web docs
• _.flatten: lodash
• _.flattenDeep: lodash
• _.flattenDepth: lodash
• Array.flatten: sugarjs