all files / src/modules/ events.ts

35.29% Statements 12/34
0% Branches 0/16
11.11% Functions 1/9
37.93% Lines 11/29
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import { ElementVNode, EventHandler, Module } from '../'
 
import { BaseModule } from './BaseModule'
import { emptyVNode } from './emptyVNode'
 
export function createEventsModule(): Module {
  return new EventsModule()
}
 
class EventsModule extends BaseModule {
  public create(vNode: ElementVNode) {
    updateEventHandlers(emptyVNode, vNode)
  }
 
  public update(formerVNode: ElementVNode, vNode: ElementVNode) {
    updateEventHandlers(formerVNode, vNode)
  }
 
  public destroy(vNode: ElementVNode) {
    updateEventHandlers(vNode, emptyVNode)
  }
}
 
function updateEventHandlers<T extends Element>(
  formerVNode: ElementVNode<T>,
  vNode: ElementVNode<T>
)
{
  const {
    element: formerElement,
    props: { on: formerOn = {}, listener: formerListener = createListener(vNode) }
  } = formerVNode
 
  const { element, props: { on = {} } } = vNode
 
  if (formerOn === on) return
 
  const listener = vNode.props.listener = formerListener
 
  for (const name in formerOn)
    if (!(on as any)[name]) formerElement.removeEventListener(name, listener, false)
 
  for (const name in on)
    if (!(formerOn as any)[name]) element.addEventListener(name, listener, false)
}
 
function createListener<T extends Element>(vNode: ElementVNode<T>): EventListener {
  return function(event: Event) {
    handleEvent<T>(event, vNode)
  }
}
 
function handleEvent<T extends Element>(event: Event, vNode: ElementVNode<T>) {
  const { type } = event
  const { props: { on = {} } } = vNode
  const handler = (on as any)[type] as EventHandler<T, Event>
 
  if (handler) handler(event as any, vNode)
}