Pro tip: type-check your JavaScript the easy way!

Sure, TypeScript isn't for everyone. But sometimes you want types and type-checking... well, turns out you can use the TypeScript compiler to check the types on your JavaScript - let me show you how!

[MaxArt]

JSDoc is actually still the only way to add a description to your functions and variables, even _TypeScript_ ones.
You can actually use it _in place_ of TypeScript types in .ts files. You can't do all the type manipulations that TypeScript allows of course, but in many cases it's enough.
I think JSDoc is the unsung hero of all this. Not many really use it correctly, and the official docs are IMO quite lackluster...

[markgoho]

So informative! Thanks Paul. You're a fantastic educator. I'm so glad you're spending some of your free time to give back to the community like this. It really helps!

[GodOfMacro]

The lowered the volume on the music worked perfectly for me, thanks for that !

[nicolasparada]

JavaScript type checking with VSCode is actually very nice.
Here is another way a bet a lot of the people didn't know.
You can define some custom types with jsdocs using @typedef then use it in other places. But you can also import these types from other files using a sort of dynamic-import like syntax, let say:
/* @param param1
For this to work, this "otherfile.js" needs to be a module. I do this thing where I create a types.js file with all my back-end data structures and a "export default undefined" at the bottom. This file is not going to be fetched from the network since it's only imported inside jsdocs.

[YousefSh]

Finally. Typescript without compiling code. I hated debugging the compiled code. Mapping files were problematic too.

[PepsT]

Wow, I thought this was going to be a pretty long video, but it was detailed and concise. Excellent!

[grantglidewell]

How do you only have 7.7k(currently) subs with this polished, concise and useful content?

[erwinheitzman]

Awesome comeback to the video from yesterday which I really enjoyed. Also your outro with the clap on the beat of the song was really awesome. Watched it twice haha, keep it up!

[SamiullahKhan]

I thought Paul gonna also mention that we can also just add type checking for just a specific file.
Just add
// @ts-check
to the top of any javascript file
Also tested with .vue file as well

[ToukiMS]

Tank for the (detailled) tips Paul :) !

[everythingisfine]

Soooo.... typescript as a devDependency & add some JSDocs and bam! Type checked JS 🥰

[accionrebeldemusical]

Thanks, Paul, this helped a lot! ^____^

[stephenisienyi]

Thanks for sharing this. I prefer writing my scripts the way you described. The script is automatically documented and free of typescript noise while benefiting fully from vscode intellisense and type checking. There is no extra parsing required to interpret the code for both machines and humans. There is no extra build step to deploy the code - simply minify away the comments . Typescript and JSDoc maintainers agreeing to collaborate has been invaluable. Much kudos to them.

[codewithyazeed]

Hi Paul, thank you! Have you tried Elm? Would love to hear your thoughts and see your fiddling with it!

[maddada]

That's helpful, however I was wondering if there was a way to set a type on variables and function parameters in the source files (like in your main.js file for example)

[davidmaxwaterman]

Is this not possible with jsdoc alone, from the command line (ie without vscode)?

[joreogan]

How can you code on this ABYSMAL keyboard

[avilde]

Nice tip, Paul ).
A bit of off-topic question - Web Assembly (WASM). Will it take over Javascript someday? For example, .NET Blazor concept.

[superchillho]

these intro's are really why I'm here.