General

Deprecated symbol used: Reports a usage of a deprecated function variable.
Destructuring properties with the same key: Reports multiple destructuring properties with identical keys.
Duplicate declaration: Reports multiple declarations in a scope.
ECMAScript specification is not followed: Reports basic syntax issues and inconsistencies with language specification, such as invalid usages of keywords, usages of incompatible numeric format, or multiple parameters to getters/setters.
Implicitly declared global JavaScript variable: Reports an implicit declaration of a global variable.
Import can be shortened: Reports an ES6 import whose from part can be shortened.
Inaccessible @private and @protected members referenced: Reports a reference to a JavaScript member that is marked with a @private or @protected tag but does not comply with visibility rules that these tags imply.
Incorrect usage of JSDoc tags: Reports warnings implied by Google Closure Compiler annotations including correct use of @abstract, @interface, and @implements tags.
JQuery selector can be optimized: Reports a duplicated jQuery selector that can be cached or a usage of an attribute or a pseudo-selector (optional).
JSX syntax used: Reports a usage of a JSX tag in JavaScript code.
Method can be made 'static': Reports a class method that can be safely made static.
Mismatched JSDoc and function signature: Reports mismatch between the names and the number of parameters within a JSDoc comment and the actual parameters of a function.
Mismatched query and update of collection: Reports a collection of fields or variables whose contents are either queried and not updated or updated and not queried.
Missed locally stored library for HTTP link: Reports a URL of an external JavaScript library that is not associated with any locally stored file.
Non-strict mode used: Reports a JavaScript file that is not in the strict mode.
Primitive type object wrapper used: Reports an improper usage of a wrapper for primitive types or a property of a primitive type being modified, as in the latter case the assigned value will be lost.
Property can be replaced with shorthand: Reports an object property that can be converted to ES6 shorthand style and provides a quick-fix to do it.
Redundant nesting in template literal: Reports nested instances of a string or a template literal.
Referencing mutable variable from closure: Reports access to outer mutable variables from functions.
Signature mismatch: Reports a JavaScript call expression where the arguments do not match the signature of the referenced function, including the types of arguments and their number.
Syntax errors and unresolved references in JSDoc: Reports a syntax discrepancy in a documentation comment.
Type mismatch: Reports incorrect type of: a parameter in a function call a return value an assigned expression TypeScript code is ignored.
Unfiltered for..in loop: Reports unfiltered for-in loops.
Unnecessary semicolon: Reports an unneeded semicolon.
Unneeded last comma in array literal: Reports a usage of a trailing comma in an array literal.
Unneeded last comma in object literal: Reports usages of a trailing comma in object literals.
Unresolved Ext JS xtype: Reports an Ext JS xtype reference that doesn't have a corresponding class.
Unresolved JSX component: Reports an unresolved reference to a JSX component.
Unresolved file reference: Reports an unresolved file reference in a JavaScript file, including CommonJS and AMD modules references.
Unresolved reference: Reports an unresolved reference in JavaScript code.
Use of possibly unassigned property in a static initializer: Reports a class member initializer which references another non-hoisted class member while the latter may be not initialized yet.
Variable declaration can be merged with the first assignment to the variable: Reports a variable that is declared without an initializer and is used much further in the code or in a single nested scope.
Webpack config compliance with JSON Schema: Validates options in webpack config files (which name should start with `webpack`, e.g.

01 April 2025