Script to generate bundle including subset of keywords

[seeden]

Hi @epoberezkin

I really like ajv. Version 5 is great because I have no problem with webpack as well.
Currently I am trying to reduce bundle size of my projects and ajv took almost 196kb / 35kb minified gziped version.
Did you think about spliting your package? or do it more modular with ES6?
Currently I am using just very simple funcionality from ajv like required properties and min max values.

Thank you for your time

[epoberezkin]

@seeden I'm not sure how Ajv can be split... Theoretically keywords can be plugins and optional, but I'm not sure I like this idea. In any case it is not related to using ES6.

For your application a better idea could be to precompile your schemas into modules using ajv-cli (that uses ajv-pack inside). It may result in a smaller bundle size (depending on the number and the size of schemas) as only a small portion of Ajv will be included in the compiled code.

[seeden]

@epoberezkin I am generating schemas on demand because they are dynamic

[epoberezkin]

You can also try using some build tools that remove unused code - e.g. if there are some Ajv methods/functions you don't use they can be removed. It requires bundling Ajv together with your app, but it's easier than managing manually what should and shouldn't be included.

[epoberezkin]

e.g. http://2ality.com/2015/12/webpack-tree-shaking.html

[seeden]

I am using webpack 2 (modules false) with uglify as well. But as I told the final size is 196kb / 35kb minified gziped version.

[epoberezkin]

196kb not minified? If so, you already remove 25%.
I can suggest forking and removing unused keywords from these two files:
https://github.com/epoberezkin/ajv/blob/master/lib/compile/_rules.js
https://github.com/epoberezkin/ajv/blob/master/lib/compile/rules.js

That should reduce the bundle substantially.
You can also contribute a script that automates generating bundle including only certain keywords (e.g. by updating and then restoring these files after the bundle is created).

[jonathansp]

Hi @epoberezkin @seeden I believe we could have the compile module imported optionally since it's not necessary and by removing it the bundle's size would be reduced substantially.

[epoberezkin]

Can you please explain?

[jonathansp]

My first thought was to remove ajv.compile function, but after going over the code I realized it is quite complex so it won't happen. The final bundle size is an issue sometimes. Our project has 5kb + 111kb from ajv.

[epoberezkin]

you can precompile your schemas with ajv-cli - the code can be smaller (unless you have large schemas, in which case it can become bigger :), as it will only include used run time parts of ajv and not the compilation logic.

[epoberezkin]

This is now possible in v7 using AjvCore (import AjvCore from "ajv/dist/code") that does not import any keywords, so only the needed keywords can be added.

The size reduction is not as substantial as may be expected - Ajv without any keywords is approximately 35% smaller than Ajv with all draft-2019-09 keywords, and 30% smaller than with draft-7 keywords - the big part is the core logic that is required for all keywords.

A bigger potential to reduce the size could be to ship with compiled schemas (PR #1332 - in progress), but it depends on the number of schemas - a compiled validation code is bigger than the schema itself - so you have to do this estimation for your application.