deep-iterator


NOTE: This is not the original branch for deep-iterator. This is a modified branch maintained by @msamblanet to incoroprate typescript definitions, convert into an ESM module, and bring dependencies up to date.

deep-iterator iterates recursively through objects, arrays, sets, maps, generic iterables, or any mix of them.

Features

- several search algorithms: bfs, dfs pre/post order
- circular references detection
- can iterate either all the nodes or just the leaves
- can skip iteration of specified objects

Installation

``
npm install deep-iterator
`

Usage

`js
import deepIterator from 'deep-iterator';
// commonJS : var deepIterator = require('deep-iterator').default;

const obj = {a: 1, b: [2, 3]};
for (let {value} of deepIterator(obj)) {
console.log(value);
}
/* outputs:
{a: 1, b: [2, 3]} (the root) - use the onlyLeaves option to remove
1
[2, 3] - use the onlyLeaves option to remove
2
3
*/

const deepArray = [[1, 2], [3, 4]];
const it = deepIterator(deepArray, {onlyLeaves: true});
for (let {parent, key} of it) {
parent[key]++;
}
// deepArray === [[2, 3], [4, 5]]
`

The node object

For each iteration, deep-iterator yields a node object containing the following members :
- value: the value of the node
- parent: the parent of the node
- key: the key of the node in its parent
- path: an array containing all the keys from the root down to the node
- parentNode: the parent node object
- isCircular(): true if the node is a circular reference
- isLeaf(): true if the node is a leaf
- type: a string representing the type of the node. Possible values are:
- Null,
- Undefined,
- Boolean,
- String,
- Symbol,
- Date,
- RegExp,
- Function,
- GeneratorFunction,
- Promise,
- Array,
- Set,
- Map,
- UserDefinedIterable: an iterable that is not an array, map, set or string,
- NonIterableObject: an object that doesn't implement the iterator protocol

Additionally, the node object contains helpers methods to determine its type, in the form of
"isType()".
Examples : isMap(), isNonIterableObject(), ...

Remarks on the node object :
- parent[key] lets you update the current node
- key is undefined if the node is the root or the iterated collection is a user defined iterable
- path and type are lazy evaluated : not using them will improve performance, i. e. :
`js
for (let {value, parent, key} of it) => path is not evaluated
for (let {value, parent, key, path} of it) => path is evaluated
`

Options

Default options are :

`js
const iterator = deepIterator(obj, {
search: 'dfsPreOrder', // DFS algorithm / parent before child
onlyLeaves: false, // all nodes are iterated
circularReference: 'leaf', // circular references are treated as leaves (not recursively iterated)
iterateOverObject: true, // non-iterable objects are iterated through their properties
skipIteration : node => false // no node are skipped
});
`

$3

accepted values: 'dfsPreOrder'(default), 'dfsPostOrder', 'bfs'

Specifies the iteration algorithm:
- dfsPreOrder: Depth First Search, parent before child
- dfsPostOrder: Depth First Search, child before parent
- bfs: Breadth First Search

$3

accepted values: false (default) or true

Iterates all the nodes or only leaves

$3

accepted values: 'leaf', 'throw', 'noCheck'

Handles the circular references detection :
- leaf: circular references are treated as leaves (no further iteration)
- throw: circular references throw an error
- noCheck: circular detection is off (this improves performances)

$3

accepted values: true(default) or false

Enables iteration over non-iterable objects or not.

$3

accepted values: callback: node => boolean

Specifies whether a recursive iteration is performed on the node or not.
- if the callback returns true : the node is not iterated itself and is considered as a leaf
- if the callback returns false : the node is deeply iterated

Note: skipIteration is not called on leaves.

Example : Skip iteration of all arrays :
`js
const it = deepIterator(obj, {skipIteration: node => Array.isArray(node.value)});
``