Avoid negating the left operand of relational operators

Docs > Code Analysis > Static Analysis Rules > Avoid negating the left operand of relational operators

Cette page n'est pas encore disponible en français, sa traduction est en cours.
Si vous avez des questions ou des retours sur notre projet de traduction actuel, n'hésitez pas à nous contacter.

Metadata

ID: javascript-best-practices/no-unsafe-negation

Language: JavaScript

Severity: Warning

Category: Best Practices

Description

Negation of the left-hand side of an expression is often unintended.

Non-Compliant Code Examples

!a in b
(!a in b)
!(a) in b
!a instanceof b
(!a instanceof b)
!(a) instanceof b

Compliant Code Examples

a in b
a in b === false
!(a in b);
(!a) in b
a instanceof b
a instanceof b === false;
!(a instanceof b);
(!a) instanceof b;

How to use this rule

1
2
rulesets:
  - javascript-best-practices     # Rules to enforce JavaScript best practices.

Create a static-analysis.datadog.yml with the content above at the root of your repository
Use our free IDE Plugins or add Code Analysis scans to your CI pipelines
Get feedback on your code

For more information, please read the Code Analysis documentation

VS Code Extension

Identify code vulnerabilities directly in your
VS Code editor

JetBrains Plugin

Identify code vulnerabilities directly in
JetBrains products