So the following code is in Angular 4 and I can't figure out why it doesn't work the way as expected.
Here is a snippet of my handler:
onUpdatingServerName(event: Event) {
console.log(event);
this.newserverName = event.target.value; //this wont work
}
HTML element:
<input type="text" class="form-control" (input)="onUpdatingServerName($event)">
The code gives me the error:
Property 'value' does not exist on type 'EventTarget'.
But as it can be seen in the console.log
that value does exist on the event.target
.
This question is related to
javascript
angular
typescript
Passing HTMLInputElement as a generic to the event type should work too:
onUpdatingServerName(event: React.ChangeEvent<HTMLInputElement>) {
console.log(event);
this.newserverName = event.target.value;
}
I was looking for a solution to a similar TypeScript error with React:
Property 'dataset' does not exist on type EventTarget in TypeScript
I wanted to get to event.target.dataset
of a clicked button element in React:
<button
onClick={onClickHandler}
data-index="4"
data-name="Foo Bar"
>
Delete Candidate
</button>
Here is how I was able to get the dataset
value to "exist" via TypeScript:
const onClickHandler = (event: React.MouseEvent<HTMLButtonElement>) => {
const { name, index } = (event.target as HTMLButtonElement).dataset
console.log({ name, index })
// do stuff with name and index…
}
You should use event.target.value
prop with onChange handler if not you could see :
index.js:1437 Warning: Failed prop type: You provided a `value` prop to a form field without an `onChange` handler. This will render a read-only field. If the field should be mutable use `defaultValue`. Otherwise, set either `onChange` or `readOnly`.
Or If you want to use other handler than onChange, use event.currentTarget.value
Here's another fix that works for me:
(event.target as HTMLInputElement).value
That should get rid of the error by letting TS know that event.target
is an HTMLInputElement
, which inherently has a value
. Before specifying, TS likely only knew that event
alone was an HTMLInputElement
, thus according to TS the keyed-in target
was some randomly mapped value that could be anything.
add any type to event
event: any
example
[element].addEvenListener('mousemove', (event: any) =>{
//CODE//
} )
what happens is that typescript adds event as Event type and for some reason it doesn't recognize some properties. Adding it of type any no longer exists this problem, this works for any document.[Property]
Try code below:
console.log(event['target'].value)
it works for me :-)
you can also create your own interface as well.
export interface UserEvent {
target: HTMLInputElement;
}
...
onUpdatingServerName(event: UserEvent) {
.....
}
The way I do it is the following (better than type assertion imho):
onFieldUpdate(event: { target: HTMLInputElement }) {
this.$emit('onFieldUpdate', event.target.value);
}
This assumes you are only interested in the target
property, which is the most common case. If you need to access the other properties of event
, a more comprehensive solution involves using the &
type intersection operator:
event: Event & { target: HTMLInputElement }
This is a Vue.js version but the concept applies to all frameworks. Obviously you can go more specific and instead of using a general HTMLInputElement
you can use e.g. HTMLTextAreaElement
for textareas.
Source: Stackoverflow.com