esquery

ESQuery is a library for querying the AST output by Esprima for patterns of syntax using a CSS style selector system. Check out the demo:

demo

The following selectors are supported:

• AST node type: ForStatement
• wildcard: *
• attribute existence: [attr]
• attribute value: [attr="foo"] or [attr=123]
• attribute regex: [attr=/foo.*/] or (with flags) [attr=/foo.*/is]
• attribute conditions: [attr!="foo"], [attr>2], [attr<3], [attr>=2], or [attr<=3]
• nested attribute: [attr.level2="foo"]
• field: FunctionDeclaration > Identifier.id
• First or last child: :first-child or :last-child
• nth-child (no ax+b support): :nth-child(2)
• nth-last-child (no ax+b support): :nth-last-child(1)
• descendant: ancestor descendant
• child: parent > child
• following sibling: node ~ sibling
• adjacent sibling: node + adjacent
• negation: :not(ForStatement)
• has: :has(ForStatement), :has(> ForStatement)
• matches-any: :is([attr] > :first-child, :last-child)
• subject indicator: !IfStatement > [name="foo"]
• class of AST node: :statement, :expression, :declaration, :function, or :pattern

Similar packages

Other packages similar to esquery

jscodeshift

jscodeshift is a toolkit for running codemods over multiple JavaScript or TypeScript files. It uses a different approach than esquery by providing a more extensive API for transforming the AST but also supports querying the AST in a way similar to esquery.

acorn

acorn is a fast, small JavaScript parser that generates an abstract syntax tree (AST). While it doesn't offer querying capabilities like esquery, it's often used in conjunction with other tools to analyze and manipulate JavaScript code.

estraverse

estraverse is a simple but powerful library for traversing and optionally modifying the AST of ECMAScript code. It doesn't use a query language like esquery but provides a programmatic way to navigate and manipulate nodes in the AST.