Frontend Plan

[wxiaoguang]

Background

The frontend needs a big refactor now.

1. web_src/index.js is too big to add new code (or modify/debug).
2. code doesn't do what it should do, eg: initVueApp/initVueComponents is quite misleading
3. Vue/fomantic/jQuery are mixed together, and we may need JSX Enable JSX support in frontend #15293
4. no easy way to pass complex data structure from backend to frontend. eg: code like var ActivityTopAuthors = {{Json .ActivityTopAuthors | SafeJS}}; is not a good idea.
5. difficult to shared data between modules, eg: how can different frontend modules get current issue index?

   gitea/templates/repo/issue/view_content/sidebar.tmpl

   Line 542 in d04e581

   <!-- I know, there is probably a better way to do this -->

6. the dependency and coupling are not clear, many frontend code work like if ( $('.xxx').length == 0) return; , we do not know what pages need this function, and these css class names may conflict. A little change may break something.
7. many events are attached to document, they may conflict. Add namespace to global click event #16833
8. some problems should be resolved by framework: Prevent double click new issue/pull/comment button #16157 , Click buttons quickly in some forms will submit repeated/duplicated requests #17111

Guideline

1. Every feature should be put in separated files/directories.
2. HTML id/css-class-name should use kebab-case.
3. HTML id/css-class-name used by JavaScript top-level selector should be unique in whole project, and should contain feature related keywords.
4. jQuery events across different features should use their own namespaces.

Plan

What frontend frameworks should be used?

• fomantic will stay as long as possible. And MVC is SEO friendly.
• jQuery is a part of fomantic.
• Vue is already used, so we can continue to use it, but we should upgrade it to Vue3 and do a refactor. Vue3 is handy to implement complex UI.
• JSX is nice to have and it works well with Vue3. But we do not choose it now (according to the discussions)
• ReactJS or other MVVM? I think it doesn't make big difference from Vue3 in this project, however if we drop Vue then we must migrate many components, not worthy.

I prefer fomantic + Vue3

How to pass backend data to frontend?

• For simple data, it can be put into HTML data-xxx tag during template rendering

• For complex data like array/map, it can be put into window.config.pageData.xxx. We write some common code to render pageData into JSON automatically in base template:

<script>
window.config.pageData = {{ .PageData }}
</script>

Then backend work will be easy:

ctx.PageData["xxx"] = someMap

How to init frontend functions in a page?

We have two choices (I prefer keep and improve current mechanism)

Frontend functions depned on templates

It is the mechanism what we are using now. In index.js it calls every init function, every init function checks whehter current page has some DOM elements. If current page has the matched DOM elements, then the feature will be loaded.

Pros:

• Simple, it doesn't change much with current mechanism

Cons:

• init functions can not have arguments
• There will be tens of init functions calls in index.js (maybe more than a hundred soon?)

Templates call frontend init functions

index.js exports init functions. Templates render scripts in HTML like this:

<script>
window.config.ready(function($gitea)) {
    $gitea.initIssueList();
    $gitea.initUserList(extraData);
}
</script>

When the page is loaded, index.js calls every function registered by window.config.ready.

Pros:

• It saves init time because only necessary functions are called.
• Flexible, template code can do more things when JavaScript modules are ready.

Cons:

• Order/dependency problem?
• Some init functions can only be called once while others are called many times?

Other suggestions?

TODO

Refactor Steps

1. (DONE) Complete a formal frontend guideline document in docs/content/doc/developers/frontend.md. The guideline can come from this draft.

2. (DONE) Split web_src/index.js into small files in web_src/features/. Add function calls to initXxx in index.js as before. This step can be done ASAP, and must be reviewed and approved quickly to prevent from further conflicts. Any new feature should be placed in web_src/features/ later.

3. (DONE) Introduce a common mechanism to pass backend data to frontend. eg: window.config.pageData.

4. (keep current mechanism) Introduce or improve a common mechanism to call page related init functions.

5. [FUTURE] Upgrade Vue from 2 to 3.

6. [DONE] If a change is made to legacy frontend code, the author should also follow the guideline to refactor related modules.

7. [FUTURE] Implement common and reusable code to resolve legacy frontend issues.

[wxiaoguang]

The draft is updated. Please help to improve.

[lafriks]

We should definitely move to vue3 and move away from jquery by rewriting parts as vue components but I hardly disagree on moving to JSX

[axifive]

Another way: save server-templates front(maybe later simplify to base functionality) and in parallel start to rewrite new with vue and api

[wxiaoguang]

@lafriks

About JSX:

Pros

• Simple syntax, just like JavaScript back-tick string (template literals), there is no different feeling when reading template literals or JSX.
• Safe, no worry about XSS in most cases
• Efficiency, the HTML structure is generated by compiler, browsers do not need to parse the HTML string to DOM (which is slow)
• Main trend, like ReactJS, Preact, Mithril, Vue3, etc, they all like JSX
• Reusable code can be written inside a Vue componment (without JSX, it's difficult to write multiple components in a single .vue file)
• If we want to move away from jQuery, we must have a simple method to construct HTML DOM, JSX is a good choice.

Cons

• Introduce a new syntax and a new compiler plugin

General speaking, I can see there is a lot of benefits when using JSX. If less a half of members disagree JSX, then we can continue?

@axifive

About server-templates and Vue and API

In my mind, this frontend refactor should be done in one or two weeks, so we just make things clear first.

I can not imagine that the frontend can be switched to Vue + API in short time, the frontend is big. It's OK for me to continue to use MVC templates (I can accept everything as long as it is clear and easy to maintain), so the MVC template is not a major problem now, and it is easy to debug and SEO-friendly. We can leave the rewriting work to each module, and choose the best solution one by one then.

[lunny]

@lafriks vue3 also supports JSX, so I don't think JSX is totally unacceptable. I think we can mix template or JSX according the situations.

[lafriks]

@wxiaoguang

Simple syntax, just like JavaScript back-tick string (template literals), there is no different feeling when reading template literals or JSX.

Not true, as it's where hard to guess what's final HTML will look like especially for large components or pages, it's also hard to debug them. And in my opinion it looks very weird that JS is mixed with HTML without any separation.

Safe, no worry about XSS in most cases

Same with Vue templates

Efficiency, the HTML structure is generated by compiler, browsers do not need to parse the HTML string to DOM (which is slow)

Same with Vue templates that are compiled to VDomNodes

Reusable code can be written inside a Vue componment (without JSX, it's difficult to write multiple components in a single .vue file)

Not true, you can write functional Vue components just as import any other utility code inside .vue components

If we want to move away from jQuery, we must have a simple method to construct HTML DOM, JSX is a good choice.

We already have - .vue files 😉

As I already have said previously JSX looks like old shity PHP code when HTML was mixed all over the place with PHP.

I have worked on large react apps where all frontend is in JSX and I know what pain in the as* it can be... 😆

There are things also in Vue that are pain to work with like vuex etc but JSX won't help with that either 😃

[lafriks]

I also don't want to seem against other parts of proposal, I fully agree that we need to make an order in fronted part, it's just that one tiny thing (jsx) I don't agree with :)