Syntax: Deltas.OPERATION(index)
Example: Deltas.CREATE(0)

Deltas are a way for the compile-time to optimize runtime operations by providing a set of predefined operations. This is useful for cases where you are performing consistent, predictable operations at a high interval, low payload situation.

There are three types of delta operations: Deltas.INSERT, Deltas.UPDATE, and Deltas.DELETE. You can provide a specified index to select the position of the VNode's children to be inserted, updated, or deleted.

  • Deltas.INSERT is used to add children at a selected index.
    Syntax: Deltas.CREATE(index)
    Example: Deltas.CREATE(0)

  • Deltas.UPDATE is used to replace children at a selected index.
    Syntax: Deltas.UPDATE(index)
    Example: Deltas.UPDATE(0)

  • Deltas.DELETE is used to remove children at a selected index.
    Syntax: Deltas.REMOVE(index)
    Example: Deltas.REMOVE(0)

You can load these operations into a delta, or an array. You can pass them inside the m function.

import { _, m, Deltas } from 'million';

const vnode = m('div', _, ['Hello World'], _, [
  tag: 'div',
  children: ['Hello World'],
  delta: [
    [0 /* DeltaTypes.INSERT */, 0],
    [1 /* DeltaTypes.UPDATE */, 0],