Having some trouble working with the DOM in Typescript. I've got a DIV element in my HTML file and when I try to access it in Typescript, I encounter the error shown below.
HTML Markup
<div class="container">
<div id="row"> </div>
</div>
Javascript Code
const show = document.getElementById('row') as HTMLElement
console.log(show)
Error Message on Console
Using document.getElementById or document.querySelector does not guarantee that you will find a matching element. This is why the return type in Typescript is specified as HTMLElement | null.
By using type assertion like as HTMLElement, you are stating that you always expect to have an HTMLElement and not a null value. Rather than just checking if an element exists, you are asserting its presence.
If your assertion turns out to be incorrect and you actually end up with null instead of an
HTMLElement</code, it will result in a runtime error when trying to manipulate properties like <code>.innerHTMLnull object.
The reason for not finding a matching element even though it appears to exist within your application cannot be determined from the information provided here.
However, I can assist you in handling the possibility of null values in your Typescript code by providing an example snippet:
const show = document.getElementById('row');
if ( show ) {
// Inside this if statement block, 'show' will definitely be an `HTMLElement`
show.innerHTML = "new inner HTML";
} else {
console.error("No element was found with id 'row'");
}<div class="container">
<div id="row"></div>
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