Optimize Mapper compiled code about chromium-bidi HOT 8 CLOSED

Maksim:

Try to compile mapper, and check its size. The vast majority of the space is taken by the CDP method definitions.

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cc @vladimir-nechaev @mathiasbynens

The first commit that integrates terser has been already merged (c.f. #221). To close this bug I need more clarification from @sadym-chromium w.r.t.:

Removing those definitions [CDP string literals describing CDP methods, which are added for development convenience and are required for the functionality]

Let me know how we can accomplish that.

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I think it could be achieved by removing the following imports in the cdp client:

import * as browserProtocol from 'devtools-protocol/json/browser_protocol.json';
import * as jsProtocol from 'devtools-protocol/json/js_protocol.json';

Perhaps instead of generating classes at runtime based on JSON definitions, we could employ a Proxy?

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I think it could be achieved by removing the following imports in the cdp client:

import * as browserProtocol from 'devtools-protocol/json/browser_protocol.json';
import * as jsProtocol from 'devtools-protocol/json/js_protocol.json';

Perhaps instead of generating classes at runtime based on JSON definitions, we could employ a Proxy?

@thiagowfx IDK how exactly to reach that, and the issue involves some research. Alex's approach looks promising.

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Additionally I'd consider adding a step verifying the compiled size in the given diapason.

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Additionally I'd consider adding a step verifying the compiled size in the given diapason.

That was a good idea! Done on #224

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https://mariusschulz.com/blog/importing-json-modules-in-typescript:

Now, we get a type error in line 2. TypeScript doesn't let us import a JSON module out of the box, just like that. This was a conscious design decision made by the TypeScript team: pulling in large JSON files could potentially consume a lot of memory, which is why we need to opt into that feature by enabling the --resolveJsonModule compiler flag:

This is likely why the bidi mapper size is quite bloated.

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Basic preprocessing with jq to filter out types and events from the JSON file:

960K    node_modules/devtools-protocol/json/browser_protocol.json =>
284K    node_modules/devtools-protocol/json/browser_protocol_commands_only.json

168K    node_modules/devtools-protocol/json/js_protocol.json =>
60K     node_modules/devtools-protocol/json/js_protocol_commands_only.json

528K => 268K (~50% size reduction)    src/.build/bidiMapper/mapper.js

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