codeql/change-notes/1.20/analysis-javascript.md

Improvements to JavaScript analysis

General improvements

• Support for popular libraries has been improved. Consequently, queries may produce better results on code bases that use the following features:

  • client-side code, for example React
  • cookies and webstorage, for example js-cookie
  • server-side code, for example hapi

• File classification has been improved to recognize additional generated files, for example files from HTML Tidy.

• The taint tracking library now recognizes flow through persistent storage, class fields, and callbacks in certain cases. This may give more results for the security queries.

New queries

Query	Tags	Purpose
Arrow method on Vue instance (js/vue/arrow-method-on-vue-instance)	reliability, frameworks/vue	Highlights arrow functions that are used as methods on Vue instances. Results are shown on LGTM by default.
Double escaping or unescaping (js/double-escaping)	correctness, security, external/cwe/cwe-116	Highlights potential double escaping or unescaping of special characters, indicating a possible violation of CWE-116. Results are shown on LGTM by default.
Incomplete regular expression for hostnames (js/incomplete-hostname-regexp)	correctness, security, external/cwe/cwe-020	Highlights hostname sanitizers that are likely to be incomplete, indicating a violation of CWE-020. Results are shown on LGTM by default.
Incomplete URL substring sanitization	correctness, security, external/cwe/cwe-020	Highlights URL sanitizers that are likely to be incomplete, indicating a violation of CWE-020. Results shown on LGTM by default.
Incorrect suffix check (js/incorrect-suffix-check)	correctness, security, external/cwe/cwe-020	Highlights error-prone suffix checks based on indexOf, indicating a potential violation of CWE-20. Results are shown on LGTM by default.
Loop iteration skipped due to shifting (js/loop-iteration-skipped-due-to-shifting)	correctness	Highlights code that removes an element from an array while iterating over it, causing the loop to skip over some elements. Results are shown on LGTM by default.
Unbound event handler receiver (js/unbound-event-handler-receiver)	Fewer false positive results	Additional ways that class methods can be bound are recognized.
Useless comparison test (js/useless-comparison-test)	correctness	Highlights code that is unreachable due to a numeric comparison that is always true or always false. Results are shown on LGTM by default.

Changes to existing queries

Query	Expected impact	Change
Client-side cross-site scripting	More true-positive results, fewer false-positive results.	This rule now recognizes WinJS functions that are vulnerable to HTML injection, and no longer flags certain safe uses of jQuery.
Insecure randomness	More results	This rule now flags insecure uses of crypto.pseudoRandomBytes.
Uncontrolled data used in network request	More results	This rule now recognizes host values that are vulnerable to injection.
Unused parameter	Fewer false-positive results	This rule no longer flags parameters with leading underscore.
Unused variable, import, function or class	Fewer false-positive results	This rule now flags fewer variables that are implictly used by JSX elements, and no longer flags variables with leading underscore.
Uncontrolled data used in path expression	Fewer false-positive results	This rule now recognizes the Express root option, which prevents path traversal.
Unneeded defensive code	More true-positive results, fewer false-positive results.	This rule now recognizes additional defensive code patterns.
Useless conditional	Fewer results	Additional defensive coding patterns are now ignored.
Useless assignment to property.	Fewer false-positive results	This rule now treats assignments with complex right-hand sides correctly.
Unsafe dynamic method access	Fewer false-positive results	This rule no longer flags concatenated strings as unsafe method names.
Unvalidated dynamic method call	More true-positive results	This rule now flags concatenated strings as unvalidated method names in more cases.
Useless conditional	More true-positive results	This rule now flags additional uses of function call values.

Changes to QL libraries

• DataFlow::SourceNode is no longer an abstract class; to add new source nodes, extend DataFlow::SourceNode::Range instead.
• Subclasses of DataFlow::PropRead are no longer automatically made source nodes; you now need to additionally define a corresponding subclass of DataFlow::SourceNode::Range to achieve this.
• The deprecated libraries semmle.javascript.DataFlow and semmle.javascript.dataflow.CallGraph have been removed; they are both superseded by semmle.javascript.dataflow.DataFlow.
• The predicate DataFlow::returnedPropWrite was intended for internal use only and is no longer available.