What Typescript type is Angular2 event

Question

If I have the following button in an html file

<button (click)="doSomething('testing', $event)">Do something</button>

Also, in the corresponding component, I have this function

doSomething(testString: string, event){
    event.stopPropagation();
    console.log(testString + ': I am doing something');
}

Is there a proper type that should be assigned to the $event input? The event parameter itself is an object, BUT if I assign it to a type object, I get an error

Property 'stopPropogation' does not exist on type object

So, what does Typescript consider the $event input?

Answer 1

Some commonly used events and their related names (MouseEvent, FocusEvent, TouchEvent, DragEvent, KeyboardEvent):

| MouseEvent | FocusEvent |  TouchEvent | DragEvent | KeyboardEvent |
|:----------:|:----------:|:-----------:|:---------:|:-------------:|
|    click   |    focus   |  touchstart |    drag   |    keypress   |
|   mouseup  |    blur    |  touchmove  |    drop   |     keyup     |
| mouseleave |   focusin  | touchcancel |  dragend  |    keydown    |
|  mouseover |  focusout  |   touchend  |  dragover |               |

The generic Event is associated to:

• close
• change
• invalid
• play
• reset
• scroll
• select
• submit
• toggle
• waiting

If you dig in Typescript's repository, dom.generated.d.ts provides a global events interface (credit goes to Eric's answer) where you may find all the event handlers mappings at line 5419:

interface GlobalEventHandlersEventMap {
    "abort": UIEvent;
    "animationcancel": AnimationEvent;
    "animationend": AnimationEvent;
    "animationiteration": AnimationEvent;
    "animationstart": AnimationEvent;
    "auxclick": MouseEvent;
    "beforeinput": InputEvent;
    "blur": FocusEvent;
    "canplay": Event;
    "canplaythrough": Event;
    "change": Event;
    "click": MouseEvent;
    "close": Event;
    "compositionend": CompositionEvent;
    "compositionstart": CompositionEvent;
    "compositionupdate": CompositionEvent;
    "contextmenu": MouseEvent;
    "cuechange": Event;
    "dblclick": MouseEvent;
    "drag": DragEvent;
    "dragend": DragEvent;
    "dragenter": DragEvent;
    "dragleave": DragEvent;
    "dragover": DragEvent;
    "dragstart": DragEvent;
    "drop": DragEvent;
    "durationchange": Event;
    "emptied": Event;
    "ended": Event;
    "error": ErrorEvent;
    "focus": FocusEvent;
    "focusin": FocusEvent;
    "focusout": FocusEvent;
    "formdata": FormDataEvent;
    "gotpointercapture": PointerEvent;
    "input": Event;
    "invalid": Event;
    "keydown": KeyboardEvent;
    "keypress": KeyboardEvent;
    "keyup": KeyboardEvent;
    "load": Event;
    "loadeddata": Event;
    "loadedmetadata": Event;
    "loadstart": Event;
    "lostpointercapture": PointerEvent;
    "mousedown": MouseEvent;
    "mouseenter": MouseEvent;
    "mouseleave": MouseEvent;
    "mousemove": MouseEvent;
    "mouseout": MouseEvent;
    "mouseover": MouseEvent;
    "mouseup": MouseEvent;
    "pause": Event;
    "play": Event;
    "playing": Event;
    "pointercancel": PointerEvent;
    "pointerdown": PointerEvent;
    "pointerenter": PointerEvent;
    "pointerleave": PointerEvent;
    "pointermove": PointerEvent;
    "pointerout": PointerEvent;
    "pointerover": PointerEvent;
    "pointerup": PointerEvent;
    "progress": ProgressEvent;
    "ratechange": Event;
    "reset": Event;
    "resize": UIEvent;
    "scroll": Event;
    "securitypolicyviolation": SecurityPolicyViolationEvent;
    "seeked": Event;
    "seeking": Event;
    "select": Event;
    "selectionchange": Event;
    "selectstart": Event;
    "slotchange": Event;
    "stalled": Event;
    "submit": SubmitEvent;
    "suspend": Event;
    "timeupdate": Event;
    "toggle": Event;
    "touchcancel": TouchEvent;
    "touchend": TouchEvent;
    "touchmove": TouchEvent;
    "touchstart": TouchEvent;
    "transitioncancel": TransitionEvent;
    "transitionend": TransitionEvent;
    "transitionrun": TransitionEvent;
    "transitionstart": TransitionEvent;
    "volumechange": Event;
    "waiting": Event;
    "webkitanimationend": Event;
    "webkitanimationiteration": Event;
    "webkitanimationstart": Event;
    "webkittransitionend": Event;
    "wheel": WheelEvent;
}

Answer 2

According to official event is of type Object, also in my case when i typecaste event to the Object it does't throw any error, but after reading documentation of angular2 found event is of type EventEmitter so you can type caste your event into EventEmitter

see here is plunkr for the same http://plnkr.co/edit/8HRA3bM0NxXrzBAjWYXc?p=preview

for more info refer here https://angular.io/docs/ts/latest/guide/template-syntax.html#!#event-binding