Writing custom Babel and ESLint plugins
Kent C. Dodds
Utah
1 wife, 3.5 kids
PayPal, Inc.
@kentcdodds
Please Stand...
... if you're physically able
What this talk is
- Basic introduction to the concept of ASTs
- (sorta) Practical demo of how to use ASTs with Babel and ESLint
- Something to get you totally psyched about using ASTs
What this talk is not
- A deep dive into parsing, tokenizing, and lexing
- Everything you need to know to be productive with ASTs
Let's
Get
STARTED!
Why
Should I care?
ESNext
ESNow
ESLint
eslint-plugin-import
Codemods
better than find/replace
no matter how good your regex skills are...
What
Is an AST?
Code for humans
const uniqueRandomArray = require('unique-random-array')
const transformersNames = require('./transformers-names.json')
const getRandomItem = uniqueRandomArray(transformersNames)
module.exports = {
all: transformersNames,
random: random,
}
function random(number) {
if (number === undefined) {
return getRandomItem()
} else {
const randomItems = []
for (let i = 0; i < number; i++) {
randomItems.push(getRandomItem())
}
return randomItems
}
}
Code for computers
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}Code for computers
For humans...
Exploring ASTs
For humans, for computers, for humans
How
Do I use them?
Let's try it out!
Resources
- JointJS: JavaScript AST Visualizer - jointjs.com/demos/javascript-ast
- Felix Kling: AST Explorer - astexplorer.net/
- Christoph Pojer: Evolving Complex Systems Incrementally | JSConf EU 2015 - kcd.im/jsconf-codemod-talk
- Ramana Venkata: How to write a codemod - kcd.im/codemod-tutorial
- Jamund Ferguson: Harnessing The Power of Abstract Syntax Trees - kcd.im/ast-power
- James Kyle: The Babel Plugin Handbook - kcd.im/babel-plugin-handbook
- James Kyle: How to Build a Compiler - kcd.im/compiler-talk
- ESLint: Working with Plugins - kcd.im/write-eslint-plugins
- ESTree "spec" - kcd.im/estree-spec
- "How Writing a Babel Plugin is like jQuery" - kcd.im/babel-query
- Babel Types Documentation - kcd.im/babel-types
Thank you!
