Can JavaScript be utilized to scan JavaScript code and identify all the URLs that the code is designed to access?

Question

Can JavaScript be utilized to scan JavaScript code and identify all the URLs that the code is designed to access?

Suppose I am working with a complete JS script stored in a string variable. Instead of running the entire script, my goal is to evaluate its code to identify the URLs it would attempt to retrieve via Ajax if executed.

While I could use regex to search for URLs within the code as text, this method may not uncover hidden URLs that have been obfuscated using functions like replace().

The solution needs to be implemented using Javascript.

Can anyone offer a hint on how this task could potentially be achieved?

Edit: To provide context, my current project involves creating a Greasemonkey script to filter out Facebook spamming scams from userscripts.org's script listing. I have already implemented a basic text search for common Facebook Ajax URLs used in scams, but scammers are finding ways to circumvent it. I need a reliable way to capture all Ajax URLs for inspection, regardless of how they have been manipulated and modified using string functions. More information can be found at .

javascript ajax search

Answer 1

Answer №1

If you're looking to intercept all AJAX calls, this topic may be of help: intercept all ajax calls?

Instead of relying on JavaScript frameworks, you can redefine XHR for custom behavior:


var ajax_urls = new Array();
var XHR_backup = new Array();
XHR_backup.open = XMLHttpRequest.prototype.open;
XHR_backup.send = XMLHttpRequest.prototype.send;

// Customize XHR behavior
(function(XHR, ajax_urls) {
    "use strict";

    var open = XHR.prototype.open;
    var send = XHR.prototype.send;

    XHR.prototype.open = function(method, url, async, user, pass) {
        ajax_urls.push(url);
    };

    XHR.prototype.send = function(data) {
    }
})(XMLHttpRequest, ajax_urls);

// Evaluate your script
eval(resultScript);

for (var i = 0; i < ajax_urls.length; i++) {
    alert('Hey, my super XHR fetched ' + ajax_urls[i] + ' !!');
}

// Restore initial XHR behavior
XMLHttpRequest.prototype.open = XHR_backup.open;
XMLHttpRequest.prototype.send = XHR_backup.send;

Edit: I have not tested this code snippet yet, so I look forward to hearing your feedback.

Edit2: Confirmed working after testing! Check it out here: http://jsfiddle.net/3qVUP/1/

Answer 2

If you're looking to intercept all AJAX calls, this topic may be of help: intercept all ajax calls?

Instead of relying on JavaScript frameworks, you can redefine XHR for custom behavior:


var ajax_urls = new Array();
var XHR_backup = new Array();
XHR_backup.open = XMLHttpRequest.prototype.open;
XHR_backup.send = XMLHttpRequest.prototype.send;

// Customize XHR behavior
(function(XHR, ajax_urls) {
    "use strict";

    var open = XHR.prototype.open;
    var send = XHR.prototype.send;

    XHR.prototype.open = function(method, url, async, user, pass) {
        ajax_urls.push(url);
    };

    XHR.prototype.send = function(data) {
    }
})(XMLHttpRequest, ajax_urls);

// Evaluate your script
eval(resultScript);

for (var i = 0; i < ajax_urls.length; i++) {
    alert('Hey, my super XHR fetched ' + ajax_urls[i] + ' !!');
}

// Restore initial XHR behavior
XMLHttpRequest.prototype.open = XHR_backup.open;
XMLHttpRequest.prototype.send = XHR_backup.send;

Edit: I have not tested this code snippet yet, so I look forward to hearing your feedback.

Edit2: Confirmed working after testing! Check it out here: http://jsfiddle.net/3qVUP/1/

Answer 3

Answer №2

If the entire content is stored in a variable, it can be treated as a string which allows for parsing to extract specific information. Utilizing Regular Expressions (RegEx) can help achieve this effectively. Explore RegEx here:

Here is an example of a RegEx pattern to identify URLs:

^http(s?)\:\/\/[0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*(:(0-9)*)*(\/?)([a-zA-Z0-9\-\.\?\,\'\/\\\+&amp;%\$#_]*)?$

Regarding Comments

To handle multiple occurrences of these strings, they can be concatenated within a BuildString() function to create a single string result. The concatenated variable can then be subjected to regex operations to extract URLs.

For example:

function Concatenation() {
    var _strOutput = "<script>var x = 0; x += " + GetVariableIterator() + "; return x; </script>";
    return _strOutput;
}

function FinalResult() {
    var _strCombined = Concatenation();
    // Apply Regex and process URLs accordingly
}

Answer 4

If the entire content is stored in a variable, it can be treated as a string which allows for parsing to extract specific information. Utilizing Regular Expressions (RegEx) can help achieve this effectively. Explore RegEx here:

Here is an example of a RegEx pattern to identify URLs:

^http(s?)\:\/\/[0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*(:(0-9)*)*(\/?)([a-zA-Z0-9\-\.\?\,\'\/\\\+&amp;%\$#_]*)?$

Regarding Comments

To handle multiple occurrences of these strings, they can be concatenated within a BuildString() function to create a single string result. The concatenated variable can then be subjected to regex operations to extract URLs.

For example:

function Concatenation() {
    var _strOutput = "<script>var x = 0; x += " + GetVariableIterator() + "; return x; </script>";
    return _strOutput;
}

function FinalResult() {
    var _strCombined = Concatenation();
    // Apply Regex and process URLs accordingly
}

Can JavaScript be utilized to scan JavaScript code and identify all the URLs that the code is designed to access?

Answer №1

Answer №2

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