episcope

ECMAScript scope analyzer

episcope

ECMAScript scope analyzer. Library provides set of functions that perform analyzes on the nodes of the AST in the de facto syntax tree format. All the API function take AST nodes denoting a lexical scope and performed static analyzes at the given scope level.

Returns array of Identifier nodes for all the free references with in the given scope that are not part of declarations or members access identifiers.

var esprima = require("esprima")
var references = require("episcope/references")
var ast = esprima.parse("console.log('>>>', error)")
references(ast)
// =>  [{ type: "Identifier", name: "console" }, { type: "Identifier", name: "error" }] 

Returns array of Identifier nodes for all the declared bindings available to the given scope, including named arguments if given scope is a function form.

var esprima = require("esprima")
var bindings = require("episcope/bindings")
var ast = esprima.parse("function foo(a, b) { var c = a + b; return c * c }")
ast.body[0].id
// => { type: 'Identifier', name: 'foo' } 
bindings(ast.body[0])
// =>  [ { type: 'Identifier', name: 'a' }, 
//       { type: 'Identifier', name: 'b' }, 
//       { type: 'Identifier', name: 'c' } ] 

Returns array of nested scope forms for the given one. Note the nested scopes of those nested scopes are not included, but this function can be used to do the walk through them too.

var esprima = require("esprima")
var scopes = require("episcope/scopes")
var ast = esprima.parse(String(function root() {
  function nested() { /***/ }
  try { /***/ } catch(error) { /***/ }
}))
ast.body[0].id
// => { type: 'Identifier', name: 'foo' } 
 
scopes(ast.body[0])
// => [ 
//  {  
//    type: 'FunctionDeclaration', 
//    id: { type: 'Identifier', name: 'nested' }, 
//    // ... 
//  }, 
//  { 
//    type: 'CatchClause', 
//    param: { type: 'Identifier', name: 'error' }, 
//    body: { type: 'BlockStatement', body: [] } 
//  } 
//] 

Returns array of Identifier nodes for all the property references within the given scope. Mainly used internally to filter out references to free variables.

var esprima = require("esprima")
var properties = require("episcope/properties")
var ast = esprima.parse("document.body.appendChild(node)")
 
properties(ast)
// => [ { type: 'Identifier', name: 'appendChild' }, 
//      { type: 'Identifier', name: 'body' } ] 
npm install episcope