Рекурсия есть:
const getFromTree = (tree, childrenKey, getter = n => n) =>
Array.isArray(tree)
? tree.flatMap(n => [
getter(n),
...getFromTree(n[childrenKey], childrenKey, getter),
])
: [];
// или
function* flatTree(tree, childrenKey) {
if (
tree instanceof Object &&
tree[Symbol.iterator] instanceof Function
) {
for (const n of tree) {
yield n;
yield* getFromTree(n[childrenKey], childrenKey);
}
}
}
Рекурсии нет:
const getFromTree = function(tree, childrenKey, getter = n => n) {
const result = [];
for (const stack = this(tree); stack.length;) {
const n = stack.pop();
result.push(getter(n));
stack.push(...this(n[childrenKey]));
}
return result;
}.bind(x => x instanceof Array ? [...x].reverse() : []);
// или
const flatTree = function*(tree, childrenKey) {
const stack = [];
for (let [ i, arr ] = this(tree); ++i < arr.length || stack.length;) {
if (i === arr.length) {
[ i, arr ] = stack.pop();
} else {
yield arr[i];
stack.push([ i, arr ]);
[ i, arr ] = this(arr[i][childrenKey]);
}
}
}.bind(x => [ -1, x?.constructor === Array ? x : [] ]);
Достаём id:
// т.к. id верхнего уровня получать не желаете, избавимся от него
const withoutTopLevel = data.flatMap(n => n.children);
// если использовать обычную функцию
const ids = getFromTree(withoutTopLevel, 'children', n => n.id);
// или, генератор
const ids = Array.from(flatTree(withoutTopLevel, 'children'), n => n.id);
