It is important to handle the possibility of null values when working with TypeScript, such as when dealing with
document.getElementById('uploadImage')
and its potential return of
null, or when accessing
.files which could also be null.
In the specific scenario where you are handling #uploadImage, adding a dummy null check or utilizing the non-null assertion can ensure smooth functionality, like so: input!.files[0].
const input = document.getElementById('uploadImage') as HTMLInputElement;
// file may be null if use canceled out of the dialog
const file = input!.files?[0]
An alternative approach involves obtaining the element from the event source, but it's crucial to acknowledge that .files might still be null:
const upload = (e: ) => {
const file= (e.target as HTMLInputElement).files?.[0];
}
Furthermore, make sure to listen for the change event rather than click, as users may not have selected anything immediately upon clicking.
To see a functioning example using plain TypeScript, check out this link. The framework being used isn't necessarily relevant to address your question.
// Non-null assertion because we know input exists.
const input: HTMLInputElement = document.querySelector("input")!;
input.addEventListener("change", function test(e: Event) {
const file = input.files?.[0];
// Properly handle possible null value for .files
console.log(file ? "File selected: " + file.name : "No file selected")
})