Method _prepareNode

packages/core/src/SpringValue.ts:528–567

* Parse the `to` and `from` range from the given `props` object. * * This also ensures the initial value is available to animated components * during the render phase.

(props: {
    to?: any
    from?: any
    reverse?: boolean
    default?: any
  })

   * during the render phase.
   */
  protected _prepareNode(props: {
    to?: any
    from?: any
    reverse?: boolean
    default?: any
  }) {
    const key = this.key || ''

    let { to, from } = props

    to = is.obj(to) ? to[key] : to
    if (to == null || isAsyncTo(to)) {
      to = undefined
    }

    from = is.obj(from) ? from[key] : from
    if (from == null) {
      from = undefined
    }

    // Create the range now to avoid "reverse" logic.
    const range = { to, from }

    // Before ever animating, this method ensures an `Animated` node
    // exists and keeps its value in sync with the "from" prop.
    if (!hasAnimated(this)) {
      if (props.reverse) [to, from] = [from, to]

      from = getFluidValue(from)
      if (!is.und(from)) {
        this._set(from)
      }
      // Use the "to" value if our node is undefined.
      else if (!getAnimated(this)) {
        this._set(to)
      }
    }

    return range
  }

  /** Every update is processed by this method before merging. */
  protected _update(