flat

Flatten nested entries to given depth.

Alternatives: flat, flatMap.

function flat(x, n, fm, ft)
// x:  nested entries
// n:  maximum depth [-1 ⇒ all]
// fm: map function (v, k, x)
// ft: test function for flatten (v, k, x) [is]

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

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

[...entries.flat(x, 1)];
// → [ [ "a", 1 ], [ "b", 2 ], [ "c", 3 ], [ "de", [ [Array], [Array] ] ] ]

[...entries.flat(x, 2)];
// → [
// →   [ "a", 1 ],
// →   [ "b", 2 ],
// →   [ "c", 3 ],
// →   [ "d", 4 ],
// →   [ "e", [ [Array] ] ]
// → ]

References

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