JetBrains Rider 2018.3 Help

Code Inspections in TypeScript



Default Severity

Equality operator may cause type coercion

Reports usages of JavaScript equality operators which may cause unexpected type coercions.It is considered a good practice to use the type-safe equality operators === and !== instead of their regular counterparts == and != .

Depending on the option selected, this will either highlight:

  • All usages of == and != operators.

  • All usages except comparison with null. Some code styles allow using x == null as a replacement for x === null || x === undefined .

  • Only suspicious expressions, such as: == or != comparisons to 0 , '' , null , true , false , or undefined .


Type mismatch

Checks TypeScript called function parameters, return values, assigned expressions to be of correct type.


Type mismatch in 'any' type context

Checks TypeScript called function parameters, return values, assigned expressions to be of correct type in 'any' type context.

Weak warning

Unresolved JavaScript variable

Checks TypeScript referenced variables and fields to be valid ones.

Weak warning

Validate imports

Validate TypeScript imports


Unresolved JavaScript function

Checks TypeScript called functions to be valid ones.

Weak warning

@private and @protected members accessibility

This inspection checks that TypeScript private and protected members are visible in current context.

Weak warning

Import can be shortened

Reports any instances of ES6 importswhose 'from' part can be shortened by importing the parent directory.


Reference to a UMD global

Report the use of references to a UMD global if the current file is a module.

Weak warning

Field is assigned only in the constructor and can be made readonly

If a private field is assigned only in the constructor, it can be made readonly.

Weak warning

Missing augmentation import

Check that current file imports the augmentation module


Explicit member types

This inspection highlights type declarations that do not match the current code style.

By default, type declarations are highlighted as redundant when the type can be inferred from context, for example:

var pi: number = 3.14

Enabling any of the options below inverts this and suggests inserting an explicit type declaration even where the type can be inferred.


Validate tsconfig.json

Validate usages of tsconfig.json properties

Suspicious parameter assignment in constructor

Warns against a common mistake in TypeScript code, when a class field is declared as a constructor parameter, and then this parameter is assigned.
In this case, the corresponding field won't be assigned, only the local parameter value is modified.


Abstract class constructor can be made protected

Suggests to make the constructor of an abstract class protected (because it is useless to have it public)

Weak warning


Runs TSLint - a linter for TypeScript.

The highlighting is based on the rule severity specified in the TSLint configuration file.Uncheck "Use rule severity from the configuration file" to use the same severity configured in this inspection for all TSLint rules.


Last modified: 18 March 2019