Array-differences NPM

array-differences

Find the differences between two arrays and their positions.

Installation

npm install array-differences --save

yarn add array-differences

Usage

import { diffArray } from 'array-differences'

const input = [0, 1, 1, 4, 1, 1]
const output = [111, 1, 112, 1, 4, 1]
const diff = diffArray(input, output)

--> [['modified', 0, 111], ['inserted', 2, 112], ['deleted', 5]]

Using a custom comparison function:

const diff = diffArray(
  [{ name: 'John' }, { name: 'Marie' }],
  [{ name: 'John' }, { name: 'Marie' }, { name: 'Chloe' }],
  (a, b) => a.name === b.name
)

--> [['inserted', 2, { name: 'Chloe' }]]

You can recontruct the second array by iterating over the differences on the first array or using the utility:

import { reconstructArray } from 'array-differences'

const reconstructed = reconstructArray(input, diff) // builds the output

// You can reconstruct in place:
reconstructArray(input, diff, true) // modifies input to recreate output from diff

Undefined values

The algorythm does not support arrays containing undefined values. Please replace your undefined values with a placeholder before applying it.

Performance on large arrays

Entry one is length m,

Entry two is length n,

Perfomance is m m n.

Therefore, it works best on smaller first arrays or if growing an array. Performance is best when differences indexes are close to one another in the array.