I am new to Rhino parser. Can i use this rhino parser in javascript code to extract the Abstract Syntax Tree of javascript code in any html file. If so ho should i start this.This is for Analyzing AST of the code for computing the ratio between keywords and words used in javascript, to identify common decryption schemes, and to calculate the occurrences of certain classes of function calls such as fromCharCode(), eval(),and some string functions that are commonly used for the decryption and execution of drive-by-download exploits.
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FYI: An AST API was added in Rhino 1.7R3McDowell– McDowell2013-01-18 13:31:28 +00:00Commented Jan 18, 2013 at 13:31
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1 Answer
As far as I know, you can't access the AST from JavaScript in Rhino. I would look at the Esprima parser though. It's a complete JavaScript parser written in JavaScript and it has a simple API for doing code analysis.
Here's a simple example that calculates the keyword to identifier ratio:
var tokens = esprima.parse(script, { tokens: true }).tokens;
var identifierCount = 0;
var keywordCount = 0;
tokens.forEach(function (token) {
if (token.type === 'Keyword') {
keywordCount++;
}
else if (token.type === 'Identifier') {
identifierCount++;
}
});
var ratio = keywordCount / identifierCount;
2 Comments
user1335906
This parser was really good the above code worked for me Thank you. Can you provide a tutorial for this parser so that i can extract the AST of javascript code of a webpage in javscript
Matthew Crumley
I haven't done much with it yet, so I don't have any experience with stuff like that. The
parse function returns the AST though, so it shouldn't be too difficult. The documentation is at esprima.org/doc/index.html and the author's blog (ariya.ofilabs.com) has some examples of how to use it. Hopefully those help.