How to use document getElementById method in TypeScript

Question

I am trying to reset HTML Form in order to clear all the values in the input fields using;

document.getElementById('myForm').reset(); 

But I can use that in typescript, it's giving me an error saying document.getElementById('myForm') may be null

How do I solve this?

Answer 1

Typescript will force you to check the value is not null if you use the strictNullChecks option (or strict which includes strictNullChecks). You can either perform the test or use a not null assertion (!). Also you will need to use a type assertion to assert the html element is an HTMLFormElement as by default it will be just an HtmlElement and reset is present only HTMLFormElement

Just an assertion Assertion:

(document.getElementById('myForm') as HTMLFormElement).reset();

Assertion with check (recommended):

let form = document.getElementById('myForm')
if(form) (form as HTMLFormElement).reset(); 

Not null assertion (if you want to access just HtmlElement member):

document.getElementById('myForm')!.click()