compare-ast

compareAst

Determine if two strings of JavaScript have equivalent abstract syntax trees. This can be useful to test tools that perform source code transformations.

API

This module exports a function with the following signature:

compareAst(expectedJsSource, actualJsSource [, options])

Examples

// Identical sources will not trigger an error:
compareAst("var a = 3; a++;", "  var a =3; a++;");

// Because whitespace is insignificant in JavaScript, two sources which
// only differ in their spacing will not trigger an error:
compareAst("var a = 3; a++;", "  var a \t=3;\na++;");

// Code that differs structurally will throw an error
compareAst("var a = 3; a++;", "var a = 3; a--;");

// Allow for "fuzzy" variable names by specifying the `varPattern` option
// as a regular expression:
compareAst(
  "var a = 3, b = 2; a += b;",
  "var __x1__ = 3, __x2__ = 2; __x1__ += __x2__;",
  { varPattern: /__x\d+__/ }
);

// Allow for "fuzzy" string values by specifying the `stringPattern` option
// as a regular expression:
compareAst(
  "var a = 'one', b = 'two', c = 'three';"
  "var a = '__s1__', b = '__s2__', c = '__s3__';",
  { stringPattern: /__s\d+__/ }
);

Tests

Run via:

$ npm test

License

Copyright (c) 2014 Mike Pennisi
Licensed under the MIT license.