README.md

update

Utility for immutable updates with simple API and with good amount of features to make it useful across different projects.

Installation

npm install @blazingedge/update --save

Usage

import update from '@blazingedge/update'

const newState = update(state, 'path.to.users[7]', {
  email: '[email protected]',
  balance: {
    amount: n => n + 100
  }
})

More examples in the article.

API

update(data, [path], change)

Arguments

• data (any): The data to update.
• [path] (Array | string): The path of the property to update.
• change (any): The change to apply.
  • if a function then it's used to compute the new value from current one,
  • if a plain object then each its value is the change for respective key/index,
  • otherwise it's the new value.

Returns

Returns updated data. When no effective changes are made, returns the same data.

REMOVE

Special value to use in a change to remove part(s) of data.

import update, { REMOVE } from '@blazingedge/update'

// Remove entire player
update(state, 'path.to.playersById[7]', REMOVE)

// Removing and setting
update(state, 'path.to.playersById', {
  [killedPlayerId]: REMOVE,
  [killedBy]: {
    kills: n => n + 1,
  }
})

Path with "*"

To apply a change to all values of an array/object, we can use "*".

update(state, 'path.to.users[*].balance.amount', n => n + 100)

update(state, 'path.to.users[*]', (user) => {
  if (Math.random() < 0.8) {
    return REMOVE
  }
  // Mark others as lucky and double the balance amount
  return update(user, {
    lucky: true,
    balance: {
      amount: n => n * 2
    }
  })
})

Path as Array

When path is passed as an array, it can also contain "filters" to selectively change multiple values of an array/object.

update(state, ['path', 'to', 'users', { lucky: true }, 'balance'], {
  limit: REMOVE,
  amount: n => n + 1000
})

A filter can be a:

• function: user => user.lucky,
• plain object with required values: { lucky: true } (use {} for "all"),
• array of indexes/keys: [2, 4, 6, 8]