Once upon a time, an unsuspecting Mozilla engineer created an API in Firefox that exposed the SpiderMonkey engine's JavaScript parser as a JavaScript API. Said engineer documented the format it produced, and this format caught on as a lingua franca for tools that manipulate JavaScript source code.
Meanwhile JavaScript is evolving. This site will serve as a community standard for people involved in building and using these tools to help evolve this format to keep up with the evolution of the JavaScript language.
The spec uses a custom syntax to describe its structures. For example, at the
time of writing, 'es2015.md' contained a description of Program as seen below
extend interface Program {
sourceType: "script" | "module";
body: [ Statement | ModuleDeclaration ];
}Copyright Mozilla Contributors and ESTree Contributors.
Licensed under Creative Commons Sharealike.
Suggested additions and modifications must follow these guidelines:
- Backwards compatible: Non-additive modifications to existing constructs will not be considered unless immense support is in favor of such changes. (eg. #65)
- Contextless: Nodes should not retain any information about their parent. ie. a
FunctionExpressionshould not be aware of if it's a concise method. (eg. #5) - Unique: Information should not be duplicated. ie. a
kindproperty should not be present onLiteralif the type can be discerned from thevalue. (eg. #61) - Extensible: New nodes should be specced to easily allow future spec additions. This means expanding the coverage of node types. ie.
MetaPropertyoverNewTargetto cover future meta properties. (eg. #32)
ESTree has benefited from the contributions of many people over the years. We'd like to thank these folks for their significant contributions to this project:
Sebastian McKenzie (Babel), Kyle Simpson (@getify), Mike Sherov (Esprima), Ariya Hidayat (Esprima), Adrian Heine (Acorn), Dave Herman (SpiderMonkey), Michael Ficarra (@michaelficarra).