Deno supports the triple-slash reference directives of types, path, lib, and no-default-lib. This lint rule checks if there is an invalid, badly-formed directive because it is most likely a mistake.

Additionally, note that only the types directive is allowed in JavaScript files. This directive is useful for telling the TypeScript compiler the location of a type definition file that corresponds to a certain JavaScript file. However, even in the Deno manual of the versions prior to v1.10 (e.g. v1.9.2), there was a wrong statement describing that one should use the path directive in such cases. Actually, the types directive should be used. See the latest manual for more detail. So this rule also detects the usage of the directive other than types in JavaScript files and suggests replacing it with the types directive.

Invalid:

JavaScript

/// <reference path="./mod.d.ts" />
/// <reference no-default-lib="true" />
/// <reference foo="bar" />

// ... the rest of the JavaScript ...

TypeScript

/// <reference foo="bar" />

// ... the rest of the TypeScript ...

Valid:

JavaScript

/// <reference types="./mod.d.ts" />
/// <reference lib="es2017.string" />

// ... the rest of the JavaScript ...

TypeScript

/// <reference types="./mod.d.ts" />
/// <reference path="./mod.d.ts" />
/// <reference lib="es2017.string" />
/// <reference no-default-lib="true" />

// ... the rest of the TypeScript ...