Package Exports

estree-walker

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (estree-walker) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

estree-walker

Simple utility for walking an ESTree-compliant AST, such as one generated by acorn.

Installation

npm i estree-walker

Usage

var walk = require( 'estree-walker' ).walk;
var acorn = require( 'acorn' );

ast = acorn.parse( sourceCode, options ); // https://github.com/marijnh/acorn

walk( ast, {
  enter: function ( node, parent ) {
    // some code happens
  },
  leave: function ( node, parent ) {
      // some code happens
  }
});

Inside the enter function, calling this.skip() will prevent the node's children being walked, or the leave function (which is optional) being called.

Why not use estraverse?

The ESTree spec is evolving to accommodate ES6/7. I've had a couple of experiences where estraverse was unable to handle an AST generated by recent versions of acorn, because it hard-codes visitor keys.

estree-walker, by contrast, simply enumerates a node's properties to find child nodes (and child lists of nodes), and is therefore resistant to spec changes. It's also much smaller. (The performance, if you're wondering, is basically identical.)

None of which should be taken as criticism of estraverse, which has more features and has been battle-tested in many more situations, and for which I'm very grateful.

License

MIT