例子：book manage Component里有个app-search-input控件，通过searchEventEmitter发送事件给自己的searchEventHandler：
search input发送事件：
super是一个subject：
和event listener相关的函数：
/**
* Wraps an event listener with a function that marks ancestors dirty and prevents default behavior,
* if applicable.
*
* @param {?} tNode The TNode associated with this listener
* @param {?} lView The LView that contains this listener
* @param {?} listenerFn The listener function to call
* @param {?} wrapWithPreventDefault Whether or not to prevent default behavior
* (the procedural renderer does this already, so in those cases, we should skip)
* @return {?}
*/
function wrapListener(tNode, lView, listenerFn, wrapWithPreventDefault) {
// Note: we are performing most of the work in the listener function itself
// to optimize listener registration.
return (/**
* @param {?} e
* @return {?}
*/
function wrapListenerIn_markDirtyAndPreventDefault(e) {
// Ivy uses `Function` as a special token that allows us to unwrap the function
// so that it can be invoked programmatically by `DebugNode.triggerEventHandler`.
if (e === Function) {
return listenerFn;
}
// In order to be backwards compatible with View Engine, events on component host nodes
// must also mark the component view itself dirty (i.e. the view that it owns).
/** @type {?} */
const startView = tNode.flags & 2 /* isComponentHost */ ?
getComponentLViewByIndex(tNode.index, lView) :
lView;
// See interfaces/view.ts for more on LViewFlags.ManualOnPush
if ((lView[FLAGS] & 32 /* ManualOnPush */) === 0) {
markViewDirty(startView);
}
/** @type {?} */
let result = executeListenerWithErrorHandling(lView, listenerFn, e);
// A just-invoked listener function might have coalesced listeners so we need to check for
// their presence and invoke as needed.
/** @type {?} */
let nextListenerFn = ((/** @type {?} */ (wrapListenerIn_markDirtyAndPreventDefault))).__ngNextListenerFn__;
while (nextListenerFn) {
// We should prevent default if any of the listeners explicitly return false
result = executeListenerWithErrorHandling(lView, nextListenerFn, e) && result;
nextListenerFn = ((/** @type {?} */ (nextListenerFn))).__ngNextListenerFn__;
}
if (wrapWithPreventDefault && result === false) {
e.preventDefault();
// Necessary for legacy browsers that don't support preventDefault (e.g. IE)
e.returnValue = false;
}
return result;
});
}
最终被book manage的listener接收到：
要获取更多Jerry的原创文章，请关注公众号"汪子熙":