Linter

Deno ships with a built-in code linter for JavaScript and TypeScript.

# lint all JS/TS files in the current directory and subdirectories
deno lint
# lint specific files
deno lint myfile1.ts myfile2.ts
# lint all JS/TS files in specified directory and subdirectories
deno lint src/
# print result as JSON
deno lint --json
# read from stdin
cat file.ts | deno lint -

For more detail, run deno lint --help.

Available rules

For a complete list of supported rules visit the deno_lint rule documentation.

Ignore directives

Files

To ignore whole file // deno-lint-ignore-file directive should placed at the top of the file:

// deno-lint-ignore-file

function foo(): any {
  // ...
}

Ignore directive must be placed before first statement or declaration:

// Copyright 2020 the Deno authors. All rights reserved. MIT license.

/**
 * Some JS doc
 */

// deno-lint-ignore-file

import { bar } from "./bar.js";

function foo(): any {
  // ...
}

You can also ignore certain diagnostics in the whole file

// deno-lint-ignore-file no-explicit-any no-empty

function foo(): any {
  // ...
}

Diagnostics

To ignore certain diagnostic // deno-lint-ignore <codes...> directive should be placed before offending line. Specifying ignored rule name is required:

// deno-lint-ignore no-explicit-any
function foo(): any {
  // ...
}

// deno-lint-ignore no-explicit-any explicit-function-return-type
function bar(a: any) {
  // ...
}

Configuration

Starting with Deno v1.14 a linter can be customized using either a configuration file or following CLI flags:

--rules-tags - List of tag names that will be run. Empty list disables all tags and will only use rules from include. Defaults to “recommended”.
--rules-exclude - List of rule names that will be excluded from configured tag sets. Even if the same rule is in include it will be excluded; in other words, --rules-exclude has higher precedence over --rules-include.
--rules-include - List of rule names that will be run. If the same rule is in exclude it will be excluded.