Typescript: Type 'null' is not assignable to type error

Question

I am getting an error while converting the following code to typescript.

const element = document.querySelector('#launcher');
if (element && element.style && element.style.display) {
    element.style.display = '';
}

error TS2339: Property 'style' does not exist on type 'Element'.

and when I assign required values for same as like below

const element: { style: any } = document.querySelector('#launcher');

then the error is on the element and that is

error TS2322: Type 'Element | null' is not assignable to type '{ style: any; }'. Type 'null' is not assignable to type '{ style: any; }'.

try using var or let instead of const

Sibiraj
– Sibiraj

2017-08-24 09:19:48 +00:00
Commented Aug 24, 2017 at 9:19 — Sibiraj
– Sibiraj, Commented Aug 24, 2017 at 9:19
Possible duplicate of querySelector in Typescript

Sibiraj
– Sibiraj

2017-08-24 09:37:25 +00:00
Commented Aug 24, 2017 at 9:37 — Sibiraj
– Sibiraj, Commented Aug 24, 2017 at 9:37

Amid · Accepted Answer · 2017-08-24 09:25:44Z

5

document.querySelector returns instance of Element. And there is not much declared in the typings for it. In order to fix the error - cast it to more specific type, for example:

const element = document.querySelector('#launcher') as HTMLInputElement;
if (element && element.style && element.style.display)
{
    element.style.display = '';
}

Basically everything that inherits from HTMLElement will do the job.

edited Aug 24, 2017 at 9:25

answered Aug 24, 2017 at 9:20

Amid

22.5k6 gold badges63 silver badges59 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Nikit Prabhu · Accepted Answer · 2017-08-24 09:28:15Z

1

I would recommend giving specific types while declaring variables.

For eg: in your case the querySelector returns value of type 'Element|null' So, you can define your element variable like this

const element: Element = document.querySelector('#launcher');

Hope this helps.

answered Aug 24, 2017 at 9:28

Nikit Prabhu

1564 bronze badges

Collectives™ on Stack Overflow

Typescript: Type 'null' is not assignable to type error

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related