This library compares two arrays or objects and returns a full diff of their differences.
ℹ️ The documentation is also available on our website!
Most existing solutions return a confusing diff format that often requires extra parsing. They are also limited to object comparison.
Superdiff provides a complete and readable diff for both arrays and objects. Plus, it supports stream and file inputs for handling large datasets efficiently, is battle-tested, has zero dependencies, and is super fast.
Import. Enjoy. 👍
I am grateful to the generous donors of Superdiff!
Superdiff exports 5 functions:
// Returns a complete diff of two objects
getObjectDiff(prevObject, nextObject)
// Returns a complete diff of two arrays
getListDiff(prevList, nextList)
// Streams the diff of two object lists, ideal for large lists and maximum performance
streamListDiff(prevList, nextList, referenceProperty)
// Checks whether two values are equal
isEqual(dataA, dataB)
// Checks whether a value is an object
isObject(data)import { getObjectDiff } from "@donedeal0/superdiff";Compares two objects and returns a diff for each value and its possible subvalues. Supports deeply nested objects of any value type.
Input
prevData: Record<string, unknown>;
nextData: Record<string, unknown>;
options?: {
ignoreArrayOrder?: boolean, // false by default,
showOnly?: {
statuses: ("added" | "deleted" | "updated" | "equal")[], // [] by default
granularity?: "basic" | "deep" // "basic" by default
}
}prevData: the original object.nextData: the new object.options-
ignoreArrayOrder: if set totrue,["hello", "world"]and["world", "hello"]will be treated asequal, because the two arrays contain the same values, just in a different order. -
showOnly: returns only the values whose status you are interested in. It takes two parameters:statuses: status you want to see in the output (e.g.["added", "equal"])granularity:basicreturns only the main properties whose status matches your query.deepcan return main properties if some of their subproperties' status match your request. The subproperties are filtered accordingly.
-
Output
type ObjectDiff = {
type: "object";
status: "added" | "deleted" | "equal" | "updated";
diff: Diff[];
};
type Diff = {
property: string;
previousValue: unknown;
currentValue: unknown;
status: "added" | "deleted" | "equal" | "updated";
// recursive diff in case of subproperties
diff?: Diff[];
};Input
getObjectDiff(
{
id: 54,
user: {
name: "joe",
- member: true,
- hobbies: ["golf", "football"],
age: 66,
},
},
{
id: 54,
user: {
name: "joe",
+ member: false,
+ hobbies: ["golf", "chess"],
age: 66,
},
}
);Output
{
type: "object",
+ status: "updated",
diff: [
{
property: "id",
previousValue: 54,
currentValue: 54,
status: "equal",
},
{
property: "user",
previousValue: {
name: "joe",
member: true,
hobbies: ["golf", "football"],
age: 66,
},
currentValue: {
name: "joe",
member: false,
hobbies: ["golf", "chess"],
age: 66,
},
+ status: "updated",
diff: [
{
property: "name",
previousValue: "joe",
currentValue: "joe",
status: "equal",
},
+ {
+ property: "member",
+ previousValue: true,
+ currentValue: false,
+ status: "updated",
+ },
+ {
+ property: "hobbies",
+ previousValue: ["golf", "football"],
+ currentValue: ["golf", "chess"],
+ status: "updated",
+ },
{
property: "age",
previousValue: 66,
currentValue: 66,
status: "equal",
},
],
},
],
}import { getListDiff } from "@donedeal0/superdiff";Compares two arrays and returns a diff for each entry. Supports duplicate values, primitive values and objects.
Input
prevList: T[];
nextList: T[];
options?: {
showOnly?: ("added" | "deleted" | "moved" | "updated" | "equal")[], // [] by default
referenceProperty?: string, // "" by default
ignoreArrayOrder?: boolean, // false by default,
considerMoveAsUpdate?: boolean // false by default
}prevList: the original list.nextList: the new list.optionsshowOnlygives you the option to return only the values whose status you are interested in (e.g.["added", "equal"]).referencePropertywill consider an object to beupdatedrather thanaddedordeletedif one of its properties remains stable, such as itsid. This option has no effect on other datatypes.ignoreArrayOrder: if set totrue,["hello", "world"]and["world", "hello"]will be treated asequal, because the two arrays contain the same values, just in a different order.considerMoveAsUpdate: if set totrueamovedvalue will be considered asupdated.
Output
type ListDiff = {
type: "list";
status: "added" | "deleted" | "equal" | "moved" | "updated";
diff: {
value: unknown;
prevIndex: number | null;
newIndex: number | null;
indexDiff: number | null;
status: "added" | "deleted" | "equal" | "moved" | "updated";
}[];
};Input
getListDiff(
- ["mbappe", "mendes", "verratti", "ruiz"],
+ ["mbappe", "messi", "ruiz"]
);Output
{
type: "list",
+ status: "updated",
diff: [
{
value: "mbappe",
prevIndex: 0,
newIndex: 0,
indexDiff: 0,
status: "equal",
},
- {
- value: "mendes",
- prevIndex: 1,
- newIndex: null,
- indexDiff: null,
- status: "deleted",
- },
- {
- value: "verratti",
- prevIndex: 2,
- newIndex: null,
- indexDiff: null,
- status: "deleted",
- },
+ {
+ value: "messi",
+ prevIndex: null,
+ newIndex: 1,
+ indexDiff: null,
+ status: "added",
+ },
+ {
+ value: "ruiz",
+ prevIndex: 3,
+ newIndex: 2,
+ indexDiff: -1,
+ status: "moved",
},
],
}// If you are in a server environment
import { streamListDiff } from "@donedeal0/superdiff/server";
// If you are in a browser environment
import { streamListDiff } from "@donedeal0/superdiff/client";Streams the diff of two object lists, ideal for large lists and maximum performance.
ℹ️ streamListDiff requires ESM support for browser usage. It will work out of the box if you use a modern bundler (Webpack, Rollup) or JavaScript framework (Next.js, Vue.js).
Input
In a server environment,
Readablerefers to Node.js streams, andFilePathrefers to the path of a file (e.g.,./list.json). Examples are provided in the #usage section below.
prevList: Readable | FilePath | Record<string, unknown>[],
nextList: Readable | FilePath | Record<string, unknown>[],
referenceProperty: keyof Record<string, unknown>,
options: {
showOnly?: ("added" | "deleted" | "moved" | "updated" | "equal")[], // [] by default
chunksSize?: number, // 0 by default
considerMoveAsUpdate?: boolean; // false by default
useWorker?: boolean; // true by default
showWarnings?: boolean; // true by default
}In a browser environment,
ReadableStreamrefers to the browser's streaming API, andFilerefers to an uploaded or local file. Examples are provided in the #usage section below.
prevList: ReadableStream<Record<string, unknown>> | File | Record<string, unknown>[],
nextList: ReadableStream<Record<string, unknown>> | File | Record<string, unknown>[],
referenceProperty: keyof Record<string, unknown>,
options: {
showOnly?: ("added" | "deleted" | "moved" | "updated" | "equal")[], // [] by default
chunksSize?: number, // 0 by default
considerMoveAsUpdate?: boolean; // false by default
useWorker?: boolean; // true by default
showWarnings?: boolean; // true by default
}prevList: the original object list.nextList: the new object list.referenceProperty: a property common to all objects in your lists (e.g.id).optionschunksSizethe number of object diffs returned by each streamed chunk. (e.g.0= 1 object diff per chunk,10= 10 object diffs per chunk).showOnlygives you the option to return only the values whose status you are interested in (e.g.["added", "equal"]).considerMoveAsUpdate: if set totrueamovedvalue will be considered asupdated.useWorker: if set totrue, the diff will be run in a worker for maximum performance. Only recommended for large lists (e.g. +100,000 items).showWarnings: if set totrue, potential warnings will be displayed in the console.
⚠️ Warning: using Readable streams may impact workers' performance since they need to be converted to arrays. Consider using arrays or files for optimal performance. Alternatively, you can turn theuseWorkeroption off.
Output
The objects diff are grouped into arrays - called chunks - and are consumed thanks to an event listener. You have access to 3 events:
data: to be notified when a new chunk of object diffs is available.finish: to be notified when the stream is finished.error: to be notified if an error occurs during the stream.
interface StreamListener<T> {
on(event: "data", listener: (chunk: StreamListDiff<T>[]) => void);
on(event: "finish", listener: () => void);
on(event: "error", listener: (error: Error) => void);
}
type StreamListDiff<T extends Record<string, unknown>> = {
currentValue: T | null;
previousValue: T | null;
prevIndex: number | null;
newIndex: number | null;
indexDiff: number | null;
status: "added" | "deleted" | "moved" | "updated" | "equal";
};Input
You can send streams, file paths, or arrays as input:
If you are in a server environment
// for a simple array
const stream = [{ id: 1, name: "hello" }]
// for a large array
const stream = Readable.from(list, { objectMode: true });
// for a local file
const stream = path.resolve(__dirname, "./list.json");
If you are in a browser environment
// for a simple array
const stream = [{ id: 1, name: "hello" }]
// for a large array
const stream = new ReadableStream({
start(controller) {
list.forEach((value) => controller.enqueue(value));
controller.close();
},
});
// for a local file
const stream = new File([JSON.stringify(file)], "file.json", { type: "application/json" });
// for a file input
const stream = e.target.files[0]; Example
const diff = streamListDiff(
[
- { id: 1, name: "Item 1" },
{ id: 2, name: "Item 2" },
{ id: 3, name: "Item 3" }
],
[
+ { id: 0, name: "Item 0" },
{ id: 2, name: "Item 2" },
+ { id: 3, name: "Item Three" },
],
"id",
{ chunksSize: 2 }
);Output
diff.on("data", (chunk) => {
// first chunk received (2 object diffs)
[
+ {
+ previousValue: null,
+ currentValue: { id: 0, name: 'Item 0' },
+ prevIndex: null,
+ newIndex: 0,
+ indexDiff: null,
+ status: 'added'
+ },
- {
- previousValue: { id: 1, name: 'Item 1' },
- currentValue: null,
- prevIndex: 0,
- newIndex: null,
- indexDiff: null,
- status: 'deleted'
- }
]
// second chunk received (2 object diffs)
[
{
previousValue: { id: 2, name: 'Item 2' },
currentValue: { id: 2, name: 'Item 2' },
prevIndex: 1,
newIndex: 1,
indexDiff: 0,
status: 'equal'
},
+ {
+ previousValue: { id: 3, name: 'Item 3' },
+ currentValue: { id: 3, name: 'Item Three' },
+ prevIndex: 2,
+ newIndex: 2,
+ indexDiff: 0,
+ status: 'updated'
+ },
]
});
diff.on("finish", () => console.log("Your data has been processed. The full diff is available."))
diff.on("error", (err) => console.log(err))import { isEqual } from "@donedeal0/superdiff";Tests whether two values are equal.
Input
a: unknown,
b: unknown,
options: {
ignoreArrayOrder: boolean; // false by default
},a: the value to be compared to the valueb.b: the value to be compared to the valuea.ignoreArrayOrder: if set totrue,["hello", "world"]and["world", "hello"]will be treated asequal, because the two arrays contain the same values, just in a different order.
isEqual(
[
{ name: "joe", age: 99 },
{ name: "nina", age: 23 },
],
[
{ name: "joe", age: 98 },
{ name: "nina", age: 23 },
],
);Output
false;import { isObject } from "@donedeal0/superdiff";Tests whether a value is an object.
Input
value: unknown;value: the value whose type will be checked.
Input
isObject(["hello", "world"]);Output
false;DoneDeal0
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Issues and pull requests are welcome!