Rule: strict-type-predicates

Warns for type predicates that are always true or always false. Works for ‘typeof’ comparisons to constants (e.g. ‘typeof foo === “string”’), and equality comparison to ‘null’/’undefined’. (TypeScript won’t let you compare ‘1 === 2’, but it has an exception for ‘1 === undefined’.) Does not yet work for ‘instanceof’. Does not warn for ‘if (x.y)’ where ‘x.y’ is always truthy. For that, see strict-boolean-expressions.

This rule requires strictNullChecks to work properly.

Notes:

Config

Not configurable.

Config examples

"strict-type-predicates": true

Schema

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