Fantasy-Map-Generator/utils/arrayUtils.js

"use strict";
// FMG utils related to arrays

// return the last element of array
function last(array) {
  return array[array.length - 1];
}

// return array of values common for both array a and array b
function common(a, b) {
  const setB = new Set(b);
  return [...new Set(a)].filter(a => setB.has(a));
}

function unique(array) {
  return [...new Set(array)];
}

// deep copy for Arrays (and other objects)
function deepCopy(obj) {
  const id = x=>x;
  const dcTArray = a => a.map(id);
  const dcObject = x => Object.fromEntries(Object.entries(x).map(([k,d])=>[k,dcAny(d)]));
  const dcAny = x => x instanceof Object ? (cf.get(x.constructor)||id)(x) : x;
  // don't map keys, probably this is what we would expect
  const dcMapCore = m => [...m.entries()].map(([k,v])=>[k, dcAny(v)]);

  const cf = new Map([
      [Int8Array, dcTArray],
      [Uint8Array, dcTArray],
      [Uint8ClampedArray, dcTArray],
      [Int16Array, dcTArray],
      [Uint16Array, dcTArray],
      [Int32Array, dcTArray],
      [Uint32Array, dcTArray],
      [Float32Array, dcTArray],
      [Float64Array, dcTArray],
      [BigInt64Array, dcTArray],
      [BigUint64Array, dcTArray],
      [Map, m => new Map(dcMapCore(m))],
      [WeakMap, m => new WeakMap(dcMapCore(m))],
      [Array, a => a.map(dcAny)],
      [Set, s => [...s.values()].map(dcAny)],
      [Date, d => new Date(d.getTime())],
      [Object, dcObject],
      // other types will be referenced
      // ... extend here to implement their custom deep copy
  ]);

  return dcAny(obj);
}