newbrict / js-analyze

Javascript code analyzer project for khan academy

JS-Analyze

Javascript code analyzer project for Khan Academy

Install

npm install
bower install
grunt

after running those you can open up build/index.html and try it out. REFRESH the page for different trials!!

Why Esprima?

So when I first read the problem I looked at both Acorn, and Esprima. I thought Acorn was a much better choice: It's faster, and smaller. I did not like Acorn's documentation however, and considering how short the parse strings will be the performance increase will hardly make a difference. Esprima has a wider contributor base than Acorn so I expect it to get faster over time anyway ( among more features and less bugs ). Also Esprima has good browser support.

How it works

Create an analyzer object ( Coffee Script )

analyzer = new Analyzer

Add whatever you would like to the whitelist or blacklist. Here are some examples:

# Must have an if statement
analyzer.whitelist.add '{ "if":{} }'

# Must have an if statement, and must NOT have a while loop
analyzer.whitelist.add '{ "if":{} }'
analyzer.blacklist.add '{ "while":{} }'

# Must have triple nested if statements, and a while loop containing a for loop
# Also must NOT have any if statements containing while loops
analyzer.whitelist.add '{ "if":{"if":{"if":{}}} }'
analyzer.whitelist.add '{ "while":{"for":{}} }'
analyzer.blacklist.add '{ "if":{"while":{}} }'

Once you have your lists set up, check them against an esprima AST

editor = ace.edit "editor"
ast = esprima.parse editor.getValue()
# Make sure the AST is valid...
analyzer.verify ast

Please see the unit tests for more examples.

Limitations

Currently you cannot look for statements like "two if statements one after another", this is because I don't prune them from the AST leads