[Event Delegation] 事件代理 #event

EventDelegation.ts

function delegationEvent(
  type: string,
  target: HTMLElement,
  selector: string,
  callback: (
    this: HTMLElement | null,
    event: Event,
    element: HTMLElement | null
  ) => any
) {
  target.addEventListener(type, function(this: HTMLElement, event: Event) {
    let ele: HTMLElement | null = event.target as HTMLElement | null;
    while (ele && !ele.matches(selector)) {
      if (ele === this) {
        ele = null;
        break;
      }
      ele = ele.parentElement;
    }
    callback.call(ele, event, ele);
  });
}