Hyperscript Tagged Markup: JSX alternative using standard tagged templates
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v-bind:id="'list-' + id"
<button [style.color]="isSpecial ? 'red' : 'green'">
Writing code, not strings, means you can do everything to it that you can do to code. You can type check code. You can lint it. You can optimize it, compile it, validate it, syntax highlight it, format it with tools like Prettier, tree shake it...
That's why I like JSX, it's Javascript all the way down. Everything is code. It's a very well designed and thought out DSL.
What if I make it my special js "syntax extension"?
Sure, stringly typed programming is sometimes a quick and dirty solution - and that's fine, even permanently, if you just don't want to invest much in whatever you're doing - which too, is fine.
But it's not a good thing. It's cheap and easy, which is sometimes something you need to settle for.
Both intellij and emacs do all of these things for Vue code. That seems to cover >90% of developers' tooling needs.
Also, code itself is a string. Code is data.
When you write templates, you get more room for optimization. Glimmer engine compiles templates to binary bytecodes to bypass JavaScript parsing. Vue3 inlines component fragments as part of the compilation step.
Glimmer compiles to bytecode, but I am not sure how that “bypass[es] JavaScript parsing” as the bytecode is evaluated by a runtime written in JS (which is obviously parsed) and that translates the bytecode into JS calls. Basically one type of parsing has been replaced with another, which is fine though not obviously faster.
Likewise, I don’t see the point with Vue since again vue templates are translated into JS calls.
Or you could just make JS calls, like React does, no runtime translation required.
It’s not obviously faster, but it’s been benchmarked to be faster. https://youtu.be/nXCSloXZ-wc
You can skip to 29:34 for the performance demo.
These are tagged templates, not strings. They work as code at runtime, and it already has support to optimize it, compile it, etc. This is JS all the way down. And spankalee mentioned below they're adding typescript support to type check the very similar lit-html, so that's coming too.
> That's why I like JSX, it's Javascript all the way down. Everything is code. It's a very well designed and thought out DSL.
It's also kind of a weird to highlight all this for a DSL that actually has to be parsed from a string to get it to be Javascript. Everything else you're talking about is tooling that had to be built special for it, not the language itself.
Why not just say "I like the style of jsx embedding and existing tools better" :)
There exists a medium-sized ecosystem of tools which supports static checks on strings inside angle brackets, a la JSX. There is a smaller-but-growing ecosystem of tools that supports static checks on strings inside backticks, a la HTM/lit-html/etc. There's no fundamental difference here.
With tagged literals you end up with runtime string parsing and concatenation.
Check out the output of the Babel plugin mentioned in the readme
> // input:
> html`<div id="foo">hello ${you}</div>`
> // output:
> React.createElement("div", { id: "foo" }, "hello ", you) options
Optimize, compile etc. what?
f`string` is literally a function call f("string"). What exactly are you "compiling and optimizing"?
> These are tagged templates, not strings. They work as code at runtime, and it already has support to optimize it, compile it, etc.
So. How exactly do they "work as code" and "have support to optimize it, compile it, etc."?
Here's HTM's main function https://github.com/developit/htm/blob/master/src/index.mjs#L...
It: concatenates strings, parses (via regexes), then concatenates again. Can someone enlighten me as to why this is awesome, is code, is optimized and compiled?
> A Babel plugin that compiles htm syntax to hyperscript, React.createElement, or just plain objects.
Secondly, the answer is Babel. Since the string's components are part of the AST, it can optimize and compile it as the original poster claimed.
The difference is so subtle as to be irrelevant. You still need to manually parse, process and assemble strings. There’s no magic. There’s no code. It’s just strings (with some values here and there).
It’s enough to see the implementation of HTM (or lit-html or any other library using tagged literals) to see that.
> the answer is Babel
Which is only mentioned once the bullshit claims about tagged literals are refuted.
Babel is not exactly the answer, but as poor man’s macros it will do.
Tagged templates are strings.
So does HTM we discuss here.
I quickly googled. sql-tag and node-sql-template-strings do a lot of string concatenation (well, of course, they have to create a SQL statement out of values passed in). sql-template parses and concatenates.
Because it's really basically all you can do, be cause tag`string` is just a function call tag("string"). There's no magic.
*edit: clarity
For example, in most threads about Vue on Reddit, the fact that you can just add Vue as a script tag and start working with it is it's most frequently cited advantage.
A small app, especially for most newbies just starting out, doesn't need webpack. But obviously they didn't read the docs and didn't even try the same with React. They just went straight for webpack, even though they shouldn't have. Not to mention CRA exists.
Same with immutable and saga. Their benefits are apparent in much bigger applications, and even then there are arguably simpler and better tools like Immer, update-immutable, redux-thunk, redux-promise-middleware or even rolling out your own middleware.
Write a method to get the list id.
And FWIW I honestly think JSX is misstep.
The difference is even more pronounced once you start typing your code.
TS/TSX = 100% typed
arbitrary template DSL = 0% typed
and now these string template based on interpolation = 5% typed: Only the dynamic values inside ${} expressions are "typed", but there are no coherence checks. DOM attribute names and values remain untyped
In the absence of any real advantage for string templates, why even bother?
So I actaully like this project, thanks for this :-)
BTW: it's similar to lit-html, t7 and hyperx
Obviously if deciding between making life easy for editor implementers or making life easier for coders, the coders win, but if something is unnecessarily difficult to build good tooling for, that’s a sign of poor design in my book. And coders will ultimately suffer too because their tooling will suck and because their code will make use of all the crazy flexibility the library allows.
I think though that the concern here is a little misplaced given the constraints that HTM and lit-html work under - which is that the template strings themselves, without the values, have to be well-formed because they're passed to the HTML parser without values.
In HTM, `<${tag}>...<${tag}${slash}>` is not possible to interpret as a possibly self-closing tag because self-closing tags are expanded before values are written into VDOM.
In lit-html `<${tag}>` is not allowed at all. So we know what the tag name will be, and what attributes and properties are bound. The same amount of type-checking is possible as with JSX.
https://beta.observablehq.com/@mbostock/hello-htm
We have our own lit-html-inspired html tagged template literals that render directly to DOM, but it’s nice to see HTM’s improved support for function attributes (e.g., onclick), spread attributes, etc.
Eventually we'll get some great parts of this approach standardized, starting with Template Instantiation, and we'll finally have a great way to create and update lots of DOM from data right in the platform.
A future d3 based on that would be very awesome too :)
Sometimes it's weird how tastes change. Same thing happened with the nigh universal hacker-ish dislike of "bondage and discipline" languages, now it's enforced formatting wherever you look.
Honestly I don't find neither JSX, or this new alternative particularly readable.
But client-side rendering and server-side rendering have different use-cases. It doesn't come down to just which is 'particularly readable'.
> If you absolutely must do JavaScript you should keep it separate of your HTML and other stuff
Why? This argument has been lost. If you're writing a rich client-side UI that makes sense to be "component-oriented", there is literally zero value in splitting each component into HTML and JS, it is a completely arbitrary 'separation by technology'.
With the exception of html comments, these are invariably antifeatures. Optional quotes/closing tags save zero to negligible typing time in exchange for added complexity for tooling and reduced readibility in many circumstances.
I can understand why these features were added to HTML5 (backward compatibility is of more benefit than prescriptivism) but I would never have thought anyone would argue that having these features in HTML1 was a good idea in retrospect!?
Adding them to a new syntax that isn't burdened with backward compat requirements seems daft.
In other words, HTM is a drop-in replacement for JSX that avoids the need for a compiler by using the corresponding language features. (At the cost of a few extra ${}s.)
lit-html and its ilk render directly to the DOM. They give similar developer ergonomics to React/JSX, but don't integrate with that ecosystem. They aren't a drop-in replacement for a JSX compiler within your React app; they're more of a competitor to the entire React paradigm.
Also of note is that, as a drop-in replacement, HTM is properties-first, like React/JSX. lit-html has you use different syntax for properties and for attributes.
Both are cool!
Edit: Composability does appear to be a feature. I agree with your description.
I'm not a JavaScript developer so this is news to me, very neat feature!
Do you have a source for that?
Before JSX came out, there were tons of templating systems that let you embed HTMLish things in JS: Handlebars, Mustache, EJS, Pug, Angular templates.
JSX’s big innovation was taking the way XHP promoted HTML to first class syntax and applying it to JS. The big difference between that and the template systems that came before it is JSX is statically analyzable (by your type checker, or by other tools), which means you can scale it to FB scale.
You're right that when it came out it's main innovation was separation of concerns and composability, but types or static analysis were not part of the value proposition at the time.
On the other hand, both TypeScript and Flow support type checking for JSX attributes (and child elements to some extent)
It's completely possible to write a type-checker for HTML templates like lit-html. In TypeScript we even have access to third-party extensible interfaces for all the elements with the HTMLElementTagNameMap, so we can check buildings to properties.
We'll be working on a lit-html type-checker for TypeScript early next year.
How do you write a type checker for something that is a string (HTM, lit-html)?
At runtime these templates are parsed by the browser's built-in HTML parser.
True. Still, it's functions and regular JS, not strings manually processed at runtime
> At runtime these templates are parsed by the browser's built-in HTML parser.
It's not the first time I've seen this ... bullshit (no other word for it). Where does it come from?
The only time it's parsed by browser's built-in HTML parser is when you manually call something like `element.innerHtml = "you string that you manually assembled in your function at runtime"`.
The browser has no idea what is contained in your tagged string. Which is painfully obvious when you actually look at the implementations of HTM: https://github.com/developit/htm/blob/master/src/index.mjs#L... or lit-html: https://github.com/Polymer/lit-html/blob/master/src/lib/temp...
NM, I'll just go back to my cave now.
Tracking whether a button is disabled or not is presentation logic.
Projecting a snapshot of business state onto a presentation is also presentation logic.
"Old school PHP application" style seldom made a distinction.
Also, you must add indirection (bad) to split things apart, and indirection doesn't necessarily pay its own rent. An example would be putting an ajax api request (a client's business concern) into a component where the <button> exists that triggers it. Collating that logic with the UI is nice until you want to reuse the logic, and it's usually cheap to extract it from a component, so you can often add indirection on an as-needed basis as you scale.