Unmatchable caret in regular expression¶
ID: js/regex/unmatchable-caret Kind: problem Security severity: Severity: error Precision: very-high Tags: - quality - reliability - correctness - regular-expressions - external/cwe/cwe-561 Query suites: - javascript-code-quality.qls - javascript-security-and-quality.qls Click to see the query in the CodeQL repository
The caret character ^ in a regular expression only matches at the beginning of the input, or (for multi-line regular expressions) at the beginning of a line. If it is preceded by a pattern that must match a non-empty sequence of (non-newline) input characters, it cannot possibly match, rendering the entire regular expression unmatchable.
Recommendation¶
Examine the regular expression to find and correct any typos.
Example¶
In the following example, the regular expression /\[^.]*\.css/ cannot match any string, since it contains a caret assertion preceded by an escape sequence that matches an opening bracket.
if (file.match(/\[^.]*\.css/)) console.log("Found it."); References¶
Mozilla Developer Network: JavaScript Regular Expressions.
Common Weakness Enumeration: CWE-561.