Kevin Powell - Community•2y ago

anyone can help me find the mdn resource for return types? example is

function add(x: number, y: number): number { return x + y; } let myAdd = function (x: number, y: number): number { return x + y; }; so basically i forgot what those were called type casting or type coercion or other

20 Replies

Jochem•2y ago

they're type annotations, and part of typescript

Aozen•2y ago

mmm let me check 1moment when it says for example the function should return an html collection or something like that which gave me hard times when i started angular is this close to type annotations

Jochem•2y ago

can you link an example? I'd honestly probably still call them type annotations, even if they're only in the documentation.

Aozen•2y ago

sadly no since last time i tried it was a year ago ( but was thing i struggled with the most) that is why i asked here

Jochem•2y ago

ok, well, I'd still call them type annotations 🙂

Aozen•2y ago

https://www.typescriptlang.org/docs/handbook/dom-manipulation.html

Documentation - DOM Manipulation

Using the DOM with TypeScript

Aozen•2y ago

mmm i willcheck it getElementById(elementId: string): HTMLElement | null; the website has example like this

Aozen•2y ago

Jochem•2y ago

that means that the thing you pass in has to be a string, and you'll get either null or an HTMLElement back

Aozen•2y ago

how do i know and where do i find those html element or html element collection or nodelist example :

querySelectorAll<K extends keyof HTMLElementTagNameMap>(selectors: K): NodeListOf<HTMLElementTagNameMap[K]>;
querySelectorAll<K extends keyof SVGElementTagNameMap>(selectors: K): NodeListOf<SVGElementTagNameMap[K]>;
querySelectorAll<E extends Element = Element>(selectors: string): NodeListOf<E>;

querySelectorAll<K extends keyof HTMLElementTagNameMap>(selectors: K): NodeListOf<HTMLElementTagNameMap[K]>;
querySelectorAll<K extends keyof SVGElementTagNameMap>(selectors: K): NodeListOf<SVGElementTagNameMap[K]>;
querySelectorAll<E extends Element = Element>(selectors: string): NodeListOf<E>;

querySelector<K extends keyof HTMLElementTagNameMap>(selectors: K): HTMLElementTagNameMap[K] | null;
querySelector<K extends keyof SVGElementTagNameMap>(selectors: K): SVGElementTagNameMap[K] | null;
querySelector<E extends Element = Element>(selectors: string): E | null;

querySelector<K extends keyof HTMLElementTagNameMap>(selectors: K): HTMLElementTagNameMap[K] | null;
querySelector<K extends keyof SVGElementTagNameMap>(selectors: K): SVGElementTagNameMap[K] | null;
querySelector<E extends Element = Element>(selectors: string): E | null;

in part 2 it returns HTMLElementTagNameMap and SVGElementTagNameMap

Jochem•2y ago

https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement htmlelement is just a standard type, found that by searching DDG for HTMLElement mdn

Aozen•2y ago

DDG ?

Jochem•2y ago

same for the collection and nodelist duck duck go, alternative to google

Aozen•2y ago

oh okay is duckduck go good for programming searches? since i am noticing google is getting worse and worse daily

Jochem•2y ago

eh, it's fine sometimes better sometimes worse

Aozen•2y ago

thank you ❤️ so how do i know all of the elements of that api? so many elements other than HTMLElement how do people know what is needed and when?

Jochem•2y ago

I just kinda wing it most of the time the distinction doesn't matter and vanilla javascript barely cares about types anyway an HTMLFormElement will have a few extra properties, but it'll still have the HTMLElement ones as well mostly just don't worry about them too much until you run into a problem

Aozen•2y ago

how do we find that element if i use typescript i think it leaves me no choice

Jochem•2y ago

typescript will complain at you and you can figure it out then just google it

Aozen•2y ago

ok okay XD thank you ❤️

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anyone can help me find the mdn resource for return types? example is