@egjs/list-differ

➕➖🔄 A module that checks the diff when values are added, removed, or changed in an array.

⚙️ Installation

1$ npm i @egjs/list-differ

1<script src="//naver.github.io/egjs-list-differ/release/latest/dist/list-differ.min.js"></script>

📖 Documentation

• See Documentation page.
• Introducing ListDiffer to track changes in data and track changes(한국어)
• How to Make Cross Framework Component(한국어)

📦 Packages

Package	Version	Description
@egjs/children-differ		A module that checks diff in DOM children.
@egjs/react-children-differ		React port of @egjs/children-differ
@egjs/ngx-children-differ		Angular port of @egjs/children-differ
@egjs/vue-children-differ		Vue.js port of @egjs/children-differ

🏃 How to use

checks the diff in array

1import ListDiffer, { diff } from "@egjs/list-differ";
2
3// script => eg.ListDiffer
4// Value is key
5const differ = new ListDiffer([1, 2, 3, 4, 5, 6, 7], e => e);
6// const result = diff([1, 2, 3, 4, 5, 6, 7], [4, 3, 6, 2, 1, 7], e => e);
7const result = differ.update([4, 3, 6, 2, 1, 7]);
8// List before update
9// [1, 2, 3, 4, 5, 6, 7]
10console.log(result.prevList);
11// Updated list
12// [4, 3, 6, 2, 1, 7]
13console.log(result.list);
14// Index array of values added to `list`
15// [2]
16console.log(result.added);
17// Index array of values removed in `prevList`
18// [5, 4]
19console.log(result.removed);
20// An array of index pairs of `prevList` and `list` with different indexes from `prevList` and `list`
21// [[3, 0], [2, 1], [1, 3], [0, 4], [6, 5]]
22console.log(result.changed);
23// The subset of `changed` and an array of index pairs that moved data directly. Indicate an array of absolute index pairs of `ordered`.(Formatted by: Array<[index of prevList, index of list]>)
24// [[3, 0], [2, 1], [1, 3]]
25console.log(result.pureChanged);
26// An array of index pairs to be `ordered` that can synchronize `list` before adding data. (Formatted by: Array<[prevIndex, nextIndex]>)
27// [[3, 0], [3, 1], [3, 2]]
28console.log(result.ordered);
29// An array of index pairs of `prevList` and `list` that have not been added/removed so data is preserved
30// [[3, 0], [2, 1], [1, 3], [0, 4], [6, 5]]
31console.log(result.maintained);

What is changed?

• changed: An array of index pairs of prevList and list with different indexes from prevList and list
• pureChanged: The subset of changed and an array of index pairs that moved data directly. Indicate an array of absolute index pairs of ordered.(Formatted by: Array<[index of prevList, index of list]>)

	changed	pureChanged:
	[[3, 0], [2, 1], [1, 3], [0, 4], [6, 5]]	[[[3, 0], [2, 1], [1, 3]]
prevList
process	-
list

What is ordered?

An array of index pairs to be ordered that can synchronize list before adding data. (Formatted by: Array<[prevIndex, nextIndex]>)

	removed -> ordered -> added
prevList
removed [5, 4]
ordered	[[3, 0], [3, 1], [3, 2]]
ordered[0] [3 => 0]
ordered[1] [3 => 1]
ordered[2] [3 => 2]
added [2]
list

Data Sync Examples

1import ListDiffer, { diff } from "@egjs/list-differ";
2
3const prevList = [1, 2, 3, 4, 5, 6, 7];
4const list = [4, 3, 6, 2, 1, 7];
5// const differ = new ListDiffer(prevList, e => e);
6// const result = differ.update(list);
7const result = diff(prevList, list, e => e);

removed => ordered => added

	removed => ordered => added
prevList
process
list

• Synchronize List

1const nextList = prevList.slice();
2result.removed.forEach(index => {
3  nextList.splice(index, 1);
4});
5result.ordered.forEach(([from, to], i) => {
6  nextList.splice(from, 1);
7  nextList.splice(to, 0, list[result.pureChanged[i][1]]);
8});
9result.added.forEach(index => {
10  nextList.splice(index, 0, list[index]);
11});
12// `nextList` is the same as `list`.
13console.log(nextList);

• Synchronize DOM

1const parentElement = document.querySelector(".parent");
2const children = parentElement.children;
3
4result.removed.forEach(index => {
5  children[index].remove();
6});
7result.ordered.forEach(([from, to]) => {
8  parentElement.insertBefore(children[from], children[from < to ? to + 1 : to]);
9});
10result.added.forEach(index => {
11  parentElement.insertBefore(document.createElement("div"), children[index]);
12});

removed => maintaind => added

	maintaind => added
prevList
process
list

• Synchronize List

1const nextList: number[] = [];
2result.removed.forEach(index => {
3  // There is a remove operation for the index.
4  // prevList[index];
5});
6result.maintained.forEach(([from, to]) => {
7  nextList[to] = list[to];
8});
9result.added.forEach(index => {
10  nextList[index] = list[index];
11});
12// `nextList` is the same as `list`.
13console.log(nextList);

• Synchronize DOM

1const parentElement = document.querySelector(".parent");
2const children = parentElement.children;
3const prevChildren: Element[] = [].slice.call(parentElement.children);
4
5result.removed.forEach(index => {
6  prevChildren[index].remove();
7});
8result.maintained.forEach(([from, to]) => {
9  parentElement.appendChild(prevChildren[from]);
10});
11result.added.forEach(index => {
12  parentElement.insertBefore(document.createElement("div"), children[index]);
13});

🙌 Contributing

See CONTRIBUTING.md.

📝 Feedback

Please file an Issue.

📜 License

@egjs/list-differ is released under the MIT license.

Copyright (c) 2019-present NAVER Corp.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.