ask whether a particular esprima node matches a CSS-like selector
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README.md

esprima-selector

Use CSS-like selectors to match nodes in an esprima abstract syntax tree (AST).

Usage

var eselector = require('esprima-selector');

If you're using a library like falafel, then you have a callback function that takes an AST node as its argument. Well, eselector.tester() accepts an array of such functions, each with a CSS-like selector for the nodes it should be called for. Example:

var eselector = require('esprima-selector');

var src = falafel(fs.readFileSync('test.js', 'utf8'), eselector.tester([
  {
    selector: '*',
    callback: function(node) {
      // Gets called for every node in the AST.
      console.log('node', node.name, node.classes);
    },
  },
  {
    selector: 'program',
    callback: function(node) {
      // Gets called for the outmost node in the AST.
      node.update(
          'var indent = []; function start() { console.log(indent.join(\'\') + \'*\'); indent.push(\'\t\') } function end() { indent.pop() }' +
          node.source());
    },
  },
  {
    selector: 'program declaration.function > block',
    callback: function(node) {
      // Gets called for every code block that's the body of a function
      // declaration.
      node.update('start();' + node.source() + 'end();');
    },
  },
]));

Quick Reference

Nodes (a.k.a. CSS 'tags')

You select these as if they were CSS tags (ex: block > statement):

  • program (the outermost node)
  • expression (e.g. variable references, math expressions, initializers)
  • statement (e.g. return, if(...) {...}, debugger)
  • clause (e.g. catch(e) {...})
  • block (e.g. {...})
  • declaration (e.g. var x = ...)
  • declarator (e.g. the x = ... part of var x = ...)
  • property (e.g. the a: part of {a: 42})
  • switch-case (e.g. case 42: ...)

Classes

You select these as if they were CSS classes (ex: .function or declaration.function):

  • identifier (e.g. variable reference)
  • literal (e.g. 42 or "foo")
  • this
  • call (e.g. a())
  • unary (e.g. -i)
  • update (e.g. i++)
  • binary (e.g. a + b)
  • array
  • assignment
  • member (e.g. a.b)
  • logical (e.g. a && b)
  • ternary (e.g. a ? b : c)
  • comma (e.g. a, b)
  • object
  • new
  • function
  • return
  • break
  • label (e.g. foo:)
  • expression
  • if
  • while
  • do-while
  • throw
  • try
  • catch
  • for
  • forin
  • switch
  • debugger
  • variable
  • branch (e.g. the {...} of if (...) {...})
  • consequent (the first branch of an if statement)
  • alternate (the else branch of an if statement)