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