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Find the AST nodes from a string of JavaScript that define scope. E.g. The outer Program scope and functions.


var scopenodes = require("scopenodes")
var fs = require("fs")
var filename = process.argv[2] || "./test/lib/nested.js"
var content = fs.readFileSync(filename).toString()
var out = scopenodes(content)
  [ { type: 'Program',
    body: [ [Object], [Object] ],
    range: [ 0, 116 ],
    loc: { start: [Object], end: [Object] },
    path: [],
    parent: null },
  { type: 'BlockStatement',
    body: [ [Object] ],
    range: [ 21, 69 ],
    loc: { start: [Object], end: [Object] },
    path: [ [Object] ],
     { type: 'FunctionDeclaration',
       id: [Object],
       params: [Object],



Will return a list of nodes from an AST (Esprima) that define scoped blocks of the provided JavaScript string.

It will add some properties to each node:

  • fnName: An attempted guess at the function name. It should always be right if the function is named.
  • path: A list of outer scopes in order of scopechain for this node
  • parent: For a FunctionDeclaration or FunctionExpression node, the declaration or expression.
  • isStrict: a boolean value as to whether THIS SCOPE SPECIFICALLY has declared strict mode. Does not account for inherited strict mode.

Naming generally works like the following, and may change as we go:

  1. If the function is named, use that name.
  2. If it is an assigment, use what it is assigned to
  3. If it is a function call argument or new argument, call it "fnName() fn argument" where fnName is the function called.
  4. If the call is complex (contains a parenthesis) attempt to remove all but the last bit. (e.g. will become ".forEach() fn argument")
  5. If the function looks like listener for an on event (e.g. foo.on('exit', ...)) call it foo.on 'exit' listener
  6. In any of the above cases if that name has already been assigned, start indexing the names like so: foo, foo{2}, foo{3}, etc.

Naming nests with scope, so if you have code such as this:

function foo() {
  function bar() {
    // ... 

The two functions would be named foo and foo>bar denoting that this bar is the one defind in the scope of foo.