tree-return

walk a tree/forest and return something, like Array.prototype.map.

function treeMap(
  tree: any[] | Record<any, any>,
  handler: (node: any[], index: number, parent: any) => any,
  isSpread = true,
  customKey?: Partial<
    Record<"retKey" | "childrenKey" | "retChildrenKey", string>
  >
)

How to use

Basic usage: walk a tree and return a forest.

import { treeMap } from "treeReturn";

const tree = {
  value: "father",
  children: [
    {
      value: "child1",
      children: [],
    },
    {
      value: "child2",
      children: [],
    },
  ],
};
const res = treeMap(tree, (currentNode, index, parent) => {
  return {
    value: currentNode.value,
    parentValue: parent?.value,
  };
});
console.log(res);
// [{
//   value: "father",
//   parentValue: undefined,
//   children: [
//     {
//       value: "child1",
//       parentValue: "father",
//       children: [],
//     },
//     {
//       value: "child2",
//       parentValue: "father",
//       children: [],
//     },
//   ],
// }];

The method always returns a array which we call it forest.

Walk a forest.

const forest = [
  {
    value: "father",
    children: [
      {
        value: "child1",
        children: [],
      },
      {
        value: "child2",
        children: [],
      },
    ],
  },
  {
    value: "father2",
    children: [
      {
        value: "child3",
        children: [],
      },
      {
        value: "child4",
        children: [],
      },
    ],
  },
];

treeMap(forest, () => {
  // do and return something
});

Add or remove a node.

// return an array to add.
treeMap(forest, currentNode => {
  return currentNode.value === "father2"
    ? [
        currentNode,
        {
          value: "extra parent",
        },
      ]
    : currentNode;
});
// return an empty array to remove
treeMap(forest, currentNode => {
  return currentNode.value === "father2" ? [] : currentNode;
});

The array you return will speared by default, you can pass false to the third argument to prevent it.

Custom key.

If your children key is child instead of children, you can pass the fourth argument.

treeMap(
  forest,
  () => {
    // do and return something
  },
  true,
  {
    childrenKey: "child",
  }
);