jsgrep / jspatch - toolkit for searching and modifying JavaScript
Jsgrep is program that searches for a particular JavaScript pattern using the abstract syntax tree (AST) of the program. This enables matching expressions based on their JavaScript meaning, rather than based on simple strings. Jspatch is a tool to take that information and programmatically modify the original source code.
Example
Jsgrep: find Javelin classes that have a 'path' property
$ jsgrep -p C "JX.install(C, { properties: { path: X } })" tests/*.js
tests/javelin.js: 'Event'
tests/javelin.js: 'URI'
Jsgrep allows easily drilling into the structure of JavaScript classes. In this example, jsgrep finds Javelin classes that contain a 'path' property. The class name is stored in the metavariable C, which will be output.
Jspatch: replace setTimeout with window.setTimeout in jQuery
$ jspatch -e 's/setTimeout( A, B )/window.setTimeout( A, B )/' tests/jquery.js
--- tests/jquery.js 2012-01-10 14:51:36.000000000 -0800
+++ /tmp/jspatch.jquery.js 2012-01-11 17:13:56.000000000 -0800
@@ -420,7 +420,7 @@
if ( (wait === true && !--jQuery.readyWait) || (wait !== true && !jQuery.isReady) ) {
// Make sure body exists, at least, in case IE gets a little overzealous (ticket #5443).
if ( !document.body ) {
- return setTimeout( jQuery.ready, 1 );
+ return window.setTimeout( jQuery.ready, 1 );
}
// Remember that the DOM is ready
@@ -1987,7 +1987,7 @@
( src === "mark" || !jQuery._data(elem, markDataKey) ) ) {
// Give room for hard-coded callbacks to fire first
// and eventually mark/queue something else on the element
- setTimeout( function() {
+ window.setTimeout( function() {
if ( !jQuery._data( elem, queueDataKey ) &&
!jQuery._data( elem, markDataKey ) ) {
jQuery.removeData( elem, deferDataKey, true );
Jspatch supports a versatile patch file format that can perform far more complex transformations as well. For more information, see the online documentation.
Installation
npm install jsgrep-toolkit
To install from source code:
git clone https://github.com/facebook/jsgrep.git
cd jsgrep
git submodule update --init
npm install
TODO
- Consider a metavar that matches but doesn't save, to prevent ambiguities.
- Rewrite forEachNode to be iterative rather than recursive (to fix ...)
- Consider support for --where/--eval and/or not-patterns
- Support for most statements in patterns
- Formally testing the pattern matchers
jspatch:
- Testing
Contributors
Jsgrep was written by Ryan Patterson at Facebook. Inspiration for this project draws heavily from pfff, a source code analyzer written at Facebook.