issue_comments

I have yet to build Datasette plugin and am unfamiliar with Pluggy. Since browsers have event handling builtin Datasette could communicate with plugins through it. Handlers register as listeners for custom Datasette events and Datasette's JS can then trigger said events.

I was also wondering if you had looked at Javascript Modules for JS plugins? With services like Skypack (https://www.skypack.dev) NPM libraries can be loaded directly into browser, no build step needed. Same goes for local JS if you adhere to ES Module spec.

If minification is required then tools such as Snowpack (https://www.snowpack.dev) could fit better. It uses https://github.com/evanw/esbuild for bundling and minification.

On plugins you'd simply:

javascript import {register} from '/assets/js/datasette' register.on({'click' : my_func})

In Datasette HTML pages' head you'd merely import these files as modules one by one.

https://github.com/mishoo/UglifyJS/issues/1905#issuecomment-300485490 says:

sourceMappingURL aren't added by default in 3.x due to one of the feature requests not to - some users are putting them within HTTP response headers instead.

So the command line for that would be:

js $ uglifyjs main.js -cmo main.min.js --source-map url=main.min.js.map

For inlining the plugins.min.js file into the Jinja templates I could use the trick described here: https://stackoverflow.com/a/41404611 - which adds a {{ include_file('file.txt') }} function to Jinja.

You'll be able to add JavaScript plugins using a bunch of different mechanisms:

• In a custom template, dropping the code in to a <script> block
• A bookmarklet that injects an extra script (I'm really excited to try this out)
• A separate script.js file that's loaded into Datasette using the "extra_js_urls" metadata option, documented here: https://docs.datasette.io/en/stable/custom_templates.html#custom-css-and-javascript
• A plugin you can install, like datasette-vega or datasette-cluster-map - since plugins can bundle their own script files that then get loaded on pages via this hook: https://docs.datasette.io/en/stable/plugin_hooks.html#extra-js-urls-template-database-table-columns-view-name-request-datasette

Amazing work! And you've put in far more work than I'd expect to reduce the payload (which is admirable).

So, to add a plugin with the current design, it goes in (a) the template or (b) a bookmarklet, right?

If I'm going to do that, it would be good if subsequent plugins that register against the load event are executed straight away. That's a bit of a weird edge-case in plugin world - it would involve the bulkier code that gets loaded redefining how datasette.plugins.register works to special-case the 'load' hook.

Maybe the tiny bootstrap code could define a datasette.plugins.onload(callbackFunction) method which gets upgraded later into something that fires straight away? Would add more bytes though.

Eventually I'd like to provide a whole bunch of other datasette.X utility functions that plugins can use - things like datasette.addTabbedContentPane() or similar.

But I don't want to inline those into the page.

So... I think the basic plugin system remains inline - maybe from an inlined file called plugins-bootstrap.js. Then a separate plugins.js contains the rest of the API functionality.

If a plugin wants to take advantage of those APIs, maybe it registers itself using datasette.plugins.register('load', () => ...) - that load hook can then be fired once the bulkier plugin code has been loaded.

I think I need to keep the mechanism whereby a plugin can return undefined in order to indicate that it has nothing to say for that specific item - that's borrowed from Pluggy and I've used it a bunch in my Python plugins. That makes the code a bit longer.

I'll write some example plugins to help me decide if the filtering-out-of-undefined mechanism is needed or not.

Using object destructuring like that is a great idea. I'm going to play with your version - it's delightfully succinct.

If you're using arrow functions, you can presumably use default parameters, not much difference in support. That would save you 9 bytes. But OTOH you need "use strict"; to use arrow functions etc, and that's 13 bytes.

Your latest 250-byte one, with use strict, gzips to 199 bytes. The following might be 292 bytes, but compresses to 204, basically the same, and works in any browser (well, IE9+) at all:

var datasette=datasette||{};datasette.plugins=function(){var d={};return{register:function(b,c,e){d[b]||(d[b]=[]);d[b].push([c,e])},call:function(b,c){c=c||{};var e=[];(d[b]||[]).forEach(function(a){a=a[0].apply(a[0],a[1].map(function(a){return c[a]}));void 0!==a&&e.push(a)});return e}}}();

Source for that is below; I replaced the [fn,parameters] because closure-compiler includes a polyfill for that, and I ran closure-compiler --language_out ECMASCRIPT3:

js var datasette = datasette || {}; datasette.plugins = (() => { var registry = {}; return { register: (hook, fn, parameters) => { if (!registry[hook]) { registry[hook] = []; } registry[hook].push([fn, parameters]); }, call: (hook, args) => { args = args || {}; var results = []; (registry[hook] || []).forEach((data) => { /* Call with the correct arguments */ var result = data[0].apply(data[0], data[1].map(parameter => args[parameter])); if (result !== undefined) { results.push(result); } }); return results; } }; })();

If you could say that all hook functions had to accept one options parameter (and could use object destructuring if they wished to only see a subset), you could have this, which minifies (to all-browser-JS) to 200 bytes, gzips to 146, and works practically the same:

js var datasette = datasette || {}; datasette.plugins = (() => { var registry = {}; return { register: (hook, fn) => { registry[hook] = registry[hook] || []; registry[hook].push(fn); }, call: (hook, args) => { var results = (registry[hook] || []).map(fn => fn(args||{})); return results; } }; })();

var datasette=datasette||{};datasette.plugins=function(){var b={};return{register:function(a,c){b[a]=b[a]||[];b[a].push(c)},call:function(a,c){return(b[a]||[]).map(function(a){return a(c||{})})}}}();

Called the same, definitions tiny bit different:

js datasette.plugins.register('numbers', ({a, b}) => a + b) datasette.plugins.register('numbers', o => o.a * o.b) datasette.plugins.call('numbers', {a: 4, b: 6})