This question already has answers here: Property 'value' does not exist on type 'EventTarget' (16 answers) Closed 17 days ago.
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
.
event.target
here is an HTMLElement
which is the parent of all HTML elements, but isn't guaranteed to have the property value
. TypeScript detects this and throws the error. Cast event.target
to the appropriate HTML element to ensure it is HTMLInputElement
which does have a value
property:
(event.target as HTMLInputElement).value
Per the documentation:
Type the $event The example above casts the $event as an any type. That simplifies the code at a cost. There is no type information that could reveal properties of the event object and prevent silly mistakes. [...] The $event is now a specific KeyboardEvent. Not all elements have a value property so it casts target to an input element.
(Emphasis mine)
Passing HTMLInputElement as a generic to the event type should work too:
onUpdatingServerName(event: React.ChangeEvent<HTMLInputElement>) {
console.log(event);
this.newserverName = event.target.value;
}
onChange
proeperty handler reference in React code though. The react handler does not expect the type to be set for the React.ChangeEvent and will show a typing error. I had to revert to (a variant of) the selected answer instead, with a cast: (event.target as HTMLInputElement).value
.
Here's another fix that works for me:
(event.target as HTMLInputElement).value
That should get rid of the error by letting TS know that event.target
is an HTMLInputElement
, which inherently has a value
. Before specifying, TS likely only knew that event
alone was an HTMLInputElement
, thus according to TS the keyed-in target
was some randomly mapped value that could be anything.
I was looking for a solution to a similar TypeScript error with React:
Property 'dataset' does not exist on type EventTarget in TypeScript
I wanted to get to event.target.dataset
of a clicked button element in React:
<button
onClick={onClickHandler}
data-index="4"
data-name="Foo Bar"
>
Delete Candidate
</button>
Here is how I was able to get the dataset
value to "exist" via TypeScript:
const onClickHandler = (event: React.MouseEvent<HTMLButtonElement>) => {
const { name, index } = (event.target as HTMLButtonElement).dataset
console.log({ name, index })
// do stuff with name and index…
}
onChange={(event: ChangeEvent<HTMLInputElement>): void => { setTextFilter(event.target.value); }}
In template -
`(keyup)="value2=$any($event.target).value"`
in component -
getInput(event: Event) {
this.value1 = (event.target as HTMLInputElement).value;
}
The way I do it is the following (better than type assertion imho):
onFieldUpdate(event: { target: HTMLInputElement }) {
this.$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.
This works for me in ANGULAR HTML Component !!
$any($event.target).value
Source Link: https://www.tektutorialshub.com/angular/property-value-does-not-exist-on-type-eventtarget-error-in-angular/
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
event.currentTarget.value
is the best approach.
To solve this problem, use the $any typecast function ($any($event.target).value)
to stop the type checking in the template.
Read more here.
you can also create your own interface as well.
export interface UserEvent {
target: HTMLInputElement;
}
...
onUpdatingServerName(event: UserEvent) {
.....
}
You can explicitly parse it into "HTMLInputElement" and then access 'value'
onUpdatingServerName(event: Event) {
console.log(event);
this.newserverName = (<HTMLInputElement>event.target).value;
}
As you know, TypeScript has been always strictly on the element data type. So, You can't directly access attributes of an element without specifying its data type. The event.target
is an HTMLElement
which is the parent of all HTML elements, but isn't guaranteed to have the property value.
So, we need to typecast the variable event.target
then only we can access the value attribute from it.
OnUpdatingServerName (event: Event) {
console.log(event);
var element = event.target as HTMLElement
this.newserverName = element.value;
}
I would recommend creating a utility type:
interface MyEvent<T extends EventTarget> extends Omit<Event, 'target'> {
target: T;
}
And then use it like this:
function onChange({ target: { value } }: MyEvent<HTMLInputElement>) => {
doSomethingWith(value);
}
Declare interface
export interface HTMLInputEvent extends Event {
target: HTMLInputElement & EventTarget;
}
which can be re-used as a type for different input events
public onChange(event: HTMLInputEvent) {
const value = event.target.value;
}
React has some interface like ChangeEvent
for onChange
, FormEvent
for onSubmit
etc
I was also trying to do similar like this below solution worked for me
handleChange (e : React.ChangeEvent<HTMLInputElement>) {
console.log(e.currentTarget.value);
}
<input
autoFocus
value={this.state.account.username}
onChange={this.handleChange}
id="username"
type="text"
className="form-control"
/>
Please try this one
<input type = 'text' [value] = 'value' (input) = 'data = $any($event.target).value'>
Try code below:
console.log(event['target'].value)
it works for me :-)
add any type to event
event: any
example
[element].addEvenListener('mousemove', (event: any) =>{
//CODE//
} )
what happens is that typescript adds "event" (click in this case) 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]
any
is perfectly fine to use in cases where the object can in fact be anything. In general, if you know what the object's properties are (like we do here), you shouldn't be using any
. If the object can have any properties, you should use any
.
Success story sharing
var element = ev.target as HTMLElement
onFieldUpdate(event: { target: HTMLInputElement }) {
in the called function. See my answer below.event.target as HtmlInputlement
event.target as HTMLInputElement