Super fast list diff algorithm. Highly optimized for operations common in virtual DOM based UI systems, specifically: prepend, append, reverse, remove all, create all. However, it performs very well in the worst case (random rearrangement) as well.

Without really researching it or benchmarking, i'm going to invoke Cunningham's Law and say that it is the fastest key-based list diff algorithm in existence for this particular application in javascript.

$ npm install dift

Params:

• prev - The old list
• next - The new list
• effect - A function that receives operations. You can execute your operations in here, or aggregate them into some buffer to be executed elsewhere, that is up to you.
• key - Return a value used to compare two list items to determine whether they are equal.

• CREATE - Receives (type = CREATE, prev = null, next = newItem, pos = positionToCreate)
• UPDATE - Receives (type = UPDATE, prev = oldItem, next = newItem)
• MOVE - Receives (type = MOVE, prev = oldItem, next = newItem, pos = newPosition)
• REMOVE - Receives (type = REMOVE, prev = oldItem)

import diff, {CREATE, UPDATE, MOVE, REMOVE} from 'dift'

function diffChildren (prevList, nextList, node) {
  diff(prevList, nextList, function (type, prev, next, pos) {
    switch (type) {
      case CREATE:
        node.insertBefore(create(next), node.childNodes[pos] || null))
        break
      case UPDATE:
        update(prev, next, prev.element)
        break
      case MOVE:
        node.insertBefore(update(prev, next), prev.element)
        break
      case REMOVE:
        node.removeChild(prev.element)
        break
    }
  })
}

List diff is extremely tricky to implement correctly. There are a lot of subtle edge cases and many of them are hard to think of a priori. To deal with this, dift has not just extensive tests but exhaustive tests. dift's tests explore the entire state space of roughly 8-10 item lists and ensure that the operations generated correctly produce the desired output.

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