Comparison with NaN¶
ID: js/comparison-with-nan
Kind: problem
Security severity:
Severity: error
Precision: very-high
Tags:
- reliability
- correctness
- external/cwe/cwe-570
- external/cwe/cwe-571
Query suites:
- javascript-security-and-quality.qls
Click to see the query in the CodeQL repository
Arithmetic comparisons with the special not-a-number value NaN are useless: nothing is considered to be equal to NaN, not even NaN itself, and similarly nothing is considered greater or less than NaN.
Recommendation¶
Use the isNaN function from the standard library to determine whether a given value is NaN.
Example¶
Instead of x === NaN, use isNaN(x).
References¶
Arvind Kumar: Javascript common mistake of comparing with NaN and not with isNaN.
Mozilla Developer Network: NaN.
Common Weakness Enumeration: CWE-570.
Common Weakness Enumeration: CWE-571.