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difference-accumulator

difference-accumulator

Accumulate differences in an object, get the total difference, reset the accumulator.

install

The normal way:

npm install difference-accumulator
const accumulator = require('difference-accumulator')

use

Create a new accumulator with the original object:

const originalData = {
    firstName: 'Bilbo',
    lastName: 'Baggins'
}
const acc = accumulator(originalData)

Apply a change:

acc.accumulate({ firstName: 'Frodo' })

Get out the sum of the changes:

acc.difference() // => { firstName: 'Frodo' } 

Undo the accumulated changes:

acc.clear()
acc.difference() // => {} 

api

acc = accumulator(originalData)

  • originalData (object, optional)

Create a new accumulator by passing in an object property.

If originalData is not specified, an object literal {} will be used.

acc.accumulate(delta)

  • delta (object, optional)

The change to be applied to the original data.

If delta is not specified, no difference will be accumulated.

For example:

acc.accumulate({
    firstName: 'Frodo'
})
acc.accumulate({
    relationships: {
        uncle: 'Bilbo'
    }
})

Will accumulate to the total delta:

const difference = {
    firstName: 'Frodo',
    relationships: {
        uncle: 'Bilbo'
    }
}
acc.difference() // => difference 

Accumulating falsey values (including undefined) will yield a difference which includes those properties:

const bagginsAccumulator = accumulator({ firstName: 'Bilbo' })
bagginsAccumulator.accumulate({ firstName: undefined })
bagginsAccumulator.difference() // => { firstName: undefined } 

Accumulating values identical to the original data will yield a difference which does not include that change:

const bagginses = accumulator({ firstName: 'Bilbo' })
bagginses.accumulate({ firstName: 'Bilbo' })
bagginses.difference() // => {} 

Note that the comparison is done using === on each property, therefore:

const justSomeGuy = accumulator({})
justSomeGuy.accumulate({ firstName: undefined })
justSomeGuy.difference() // => {} 

acc.difference()

This will yield the current total accumulated difference.

acc.clear()

This will clear the total accumulated difference.

license

Published and released under the Very Open License.