3 ms·
If it's just a variable in scope, you could do: if (condition) { // new scope const jsx = // ... return <foo/> } In practice, "variable in sco
by 90s_dev 1y ago
If it's just a variable in scope, you could do:
if (condition) {
// new scope
const jsx = // ...
return <foo/>
}
In practice, "variable in scope" is essentially the same as "global in scope" and React used to require you to import 'react' at the top of every JSX file for this reason. Your solution is tantamount to just changing that to import jsx from 'react' but still requiring it explicitly.
The main problem with this is that it's non-trivial to make sure variables are in scope before/while loading a file, and they should be loaded on an as-needed basis instead of always, which is what inevitably ends up happening when you need React classic, you import React at the top of every HTML file. These problems seem to be what led to auto-imports.
I admit that my solution still does require you do something like import interpretJsx from 'something', and even further it requires you to manually call interpretJsx(<foo/>) which can be tedious and verbose.
The main benefit is that at least it becomes a standard. And besides, we probably won't need to call those functions everywhere, just at the top of a tree, like the same place you call React.render(root)
The main downside is lack of monomorphism, especially if you're passing an entire tree to interpretJsx(). I admit this is not solved by my proposal. But I still wanted to put the proposal out before smarter eyes than mine anyway.
- WorldMaker 1y agoA problem with going straight to objects is you potentially create a lot of GC churn if the `interpretJsx()` converts it to a different data structure. Also because it is a tree structure, you are probably talking a recursive depth-first-search or other tree-walker algorithm that can easily blow up the stack while it works. If you are doing something Virtual DOM-like and evaluating lots of trees, that memory/GC and CPU churn compound quickly. This is part of why JSX has always been function calls rather than a data structure to interpret: the recursion to walk the tree is flattened at "compile time". I don't see why it is a problem you'd need to import your `jsx` function in every file that uses JSX syntax, but perhaps because that's how I've always preferred to use JSX, even with React. Explicit imports are better than implicit ones. If you use lit-html you have to import its `html` function everywhere to get html`` template literals to work. It's not a lot of overhead and it works well. You can add the auto-import smarts to your editor, to your snippet files and template files. Typescript already has a ton of auto-import suggestions as you write a file.
- 90s_dev 1y agoYeah I guess you're right. This proposal has serious performance issues. Still, I don't like the React-classic style, the React-autoimport style, or the hybrid that you're advocating for. None work be very ergonomic and require tooling to at least give you errors that you forgot an import, which defeats the purpose of standardizing it at that point.