object-diffy
A Node.js library for diffing objects with nested JSON-like data.
Features:
- Diff result output is human readable and doesn't require a manual
- Contains functions to apply and reverse a diff
- Can be used for deep equality checks
- Single file with 200 lines of plain Node.js code and no dependencies
Installation
npm install object-diffyUsage
const { diff, applyDiff, reverseDiff, isEqual } = require('object-diffy')
const assertEqual = require('assert').deepStrictEqual
const date = new Date()
const fromObj = {
date,
foo: 1,
bar: [{baz: 2}]
}
const toObj = {
date,
foo: '1',
bar: [],
bla: true
}
const diffResult = diff(fromObj, toObj)
assertEqual(
diffResult,
{
foo: {type: 'updated', from: 1, to: '1', fromType: 'number', toType: 'string'},
'bar.0': {type: 'deleted', from: {baz: 2}, to: undefined},
bla: {type: 'added', from: undefined, to: true}
}
)
assertEqual(
applyDiff(fromObj, diffResult),
toObj
)
assertEqual(
reverseDiff(toObj, diffResult),
fromObj
)
assertEqual(
isEqual({foo: 1}, {foo: 1}),
true
)
assertEqual(
isEqual({foo: 1}, {foo: '1'}),
false
)Options
By default the diff function will traverse the object tree from the top level all the way down
through arrays and child objects to the leaf values. In some circumstances maybe especially for small
object and arrays this may not be ideal as it can be hard to see the context and get an overview.
To help with this problem there is a way to tune the granularity/depth of the diff function with the recurseIf option as shown below:
const { diff } = require('object-diffy')
const assertEqual = require('assert').deepStrictEqual
const fromObj = {
foo: {
bar: 1,
baz: {
bla: 2
}
},
boo: [1, 2, 3]
}
const toObj = {
foo: {
bar: 2,
baz: {
bla: 3
}
},
boo: [3, 2, 1]
}
assertEqual(
diff(fromObj, toObj),
{
'foo.bar': { type: 'updated', from: 1, to: 2 },
'foo.baz.bla': { type: 'updated', from: 2, to: 3 },
'boo.0': { type: 'updated', from: 1, to: 3 },
'boo.2': { type: 'updated', from: 3, to: 1 }
}
)
// Configure the diff function to not recurse into arrays and not
// recurse beyond the second nesting level
const recurseIf = (value, path) => !Array.isArray(value) && path.length <= 1
const options = { recurseIf }
assertEqual(
diff(fromObj, toObj, options),
{
'foo.bar': { type: 'updated', from: 1, to: 2 },
'foo.baz': { type: 'updated', from: { bla: 2 }, to: { bla: 3 } },
'boo': { type: 'updated', from: [ 1, 2, 3 ], to: [ 3, 2, 1 ] }
}
)
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent