esquery

A query library for ECMAScript AST using a CSS selector like query language.

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: *
• Node attribute existence: [attr]
• Node attribute value: [attr="foo"] or [attr=123]
• Node attribute regex: [attr=/foo.*/]
• Node attribute conditons: [attr!="foo"], [attr>2], [attr<3], [attr>=2], or [attr<=3]
• Nested node attribute: [attr.level2="foo"]
• First or last child: :first-child or :last-child
• nth-child from beginning (1 based index, no ax+b support): :nth-child(2)
• nth-last-child from end (1 based index, no ax+b support): :nth-last-child(1)
• descendant: ancestor descendant
• child: parent > child
• sibling: node ~ sibling
• adjacent: node + adjacent
• Negation: :not(ForStatement)
• Matches any pseudo selector: :matches([attr] > :first-child, :last-child)
• Selector subject (like css4, postfix only): IfStatement! > [name="foo"]