ESLint: under the hood

• the-super-tiny-compiler

  19 27,396 0.0 JavaScript

  :snowman: Possibly the smallest compiler ever

Now, those concepts are a whole entire world to explore, and this is out of the scope of this article. I suggest the reading of the Chapters 4, 5 and 6 of the book Crafting Interpreters by Robert Nystrom for a wider (but still practical) understanding of those subjects. Another practical great resource to look at is The SuperTiny Compiler. To explore them from a theorical point of view, you can find A LOT of resources from books or courses online.

• esprima

  8 6,962 0.0 TypeScript

  ECMAScript parsing infrastructure for multipurpose analysis

  

Focusing again on ESLint, the parser used by the linter is called Espree. This is an in-house parser built by the ESLint folks to fully support ECMAScript 6 and JSX on top of the already existing Esprima. The Espree module provide APIs for both tokenization and parsing that you can easily test out.

• SurveyJS

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• espree

  5 2,241 6.5 JavaScript

  An Esprima-compatible JavaScript parser

  

Focusing again on ESLint, the parser used by the linter is called Espree. This is an in-house parser built by the ESLint folks to fully support ECMAScript 6 and JSX on top of the already existing Esprima. The Espree module provide APIs for both tokenization and parsing that you can easily test out.

• astexplorer

  43 5,942 6.0 JavaScript

  A web tool to explore the ASTs generated by various parsers.

The rule that I want to write will be called not-allows-underscore: the idea is to abolish the use of underscores when declaring variables or functions. It's a real dummy rule, but it should be enough to see in action the concepts that we have discussed earlier. The first thing that I would do is to go to AST Explorer, write down a code that declares variables and functions (both standard and arrows one) and take a look at what type of node is the one that encodes the identifier. Doing that, I found out that the node type of my interest is Identifier, what a surprise! 🤣. In particular, the structure of the node holds the string used as identifier in the name property.

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