deno check

deno check type-checks your TypeScript (or JavaScript) code without running it. This is useful in CI pipelines or before deploying to catch type errors early. For more on TypeScript in Deno, see the TypeScript guide.

Basic usage

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deno check main.ts

Check multiple files:

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deno check src/server.ts src/utils.ts

Scoping and excluding files

You can pass directories or globs as positional arguments to type-check a whole tree at once:

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deno check src/
deno check "src/**/*.ts"

To skip files or directories, use the top-level exclude field in deno.json. It applies to deno check along with other subcommands like deno fmt and deno lint:

deno.json

{
  "exclude": ["dist/", "vendor/", "**/*.generated.ts"]
}

See include and exclude in the configuration reference for the full glob syntax, including how to un-exclude a sub-path.

Type-checking remote modules

By default, only local modules are type-checked. Use --all to also type-check remote dependencies:

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deno check --all main.ts

Type-checking JavaScript files

If you have a JavaScript project and want to type-check it without adding // @ts-check to every file, use the --check-js flag:

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deno check --check-js main.js

Using in CI

deno check exits with a non-zero status code if there are type errors, making it suitable for CI pipelines:

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deno check main.ts && echo "Types OK"

Note that deno test and deno bench already perform type-checking by default, so you don't need a separate deno check step if you're already running tests. Use deno check when you want to type-check without running anything — for example, as a fast early step in CI:

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deno check main.ts
deno lint
deno test

Command line usage:

deno check [OPTIONS] [file]...

Download and type-check without execution.

deno check jsr:@std/http/file-server

Unless --reload is specified, this command will not re-download already cached dependencies

Dependency management options

--frozen<BOOLEAN>optional

Error out if lockfile is out of date.

--import-map<FILE>

Load import map file from local file or remote URL.

--lock<FILE>optional

Check the specified lock file. (If value is not provided, defaults to "./deno.lock").

--no-lock

Disable auto discovery of the lock file.

--no-npm

Do not resolve npm modules.

--no-remote

Do not resolve remote modules.

--node-modules-dir<MODE>optional

Selects the node_modules directory mode for npm packages (not a path). One of: auto (create a local node_modules directory and install npm packages into it), manual (use the existing local node_modules directory, do not modify it), none (do not use a local node_modules directory; resolve npm packages from the global cache). Defaults to auto when the flag is passed without a value.

--node-modules-linker<MODE>

Sets the linker mode for npm packages (isolated or hoisted).

--reload, -r<CACHE_BLOCKLIST>optional

Reload source code cache (recompile TypeScript). With no value, reloads everything. Pass a comma-separated list of specifiers to reload only those modules; npm: reloads all npm modules; npm:chalk reloads a single npm module; jsr:@std/http/file-server,jsr:@std/assert/assert-equals reloads specific modules.

--vendor<vendor>optional

Toggles local vendor folder usage for remote modules and a node_modules folder for npm packages.

Options

--all

Type-check all code, including remote modules and npm packages.

--allow-import, -I<IP_OR_HOSTNAME>optional

Allow importing from remote hosts. Optionally specify allowed IP addresses and host names, with ports as necessary. Default value: deno.land:443,jsr.io:443,esm.sh:443,raw.esm.sh:443,cdn.jsdelivr.net:443,raw.githubusercontent.com:443,gist.githubusercontent.com:443.

--cert<FILE>

Load certificate authority from PEM encoded file.

--check-js

Enable type-checking of JavaScript files (equivalent to compilerOptions.checkJs: true).

--conditions<conditions>

Use this argument to specify custom conditions for npm package exports. You can also use DENO_CONDITIONS env var. .

--config, -c<FILE>

Configure different aspects of deno including TypeScript, linting, and code formatting. Typically the configuration file will be called deno.json or deno.jsonc and automatically detected; in that case this flag is not necessary.

--deny-import<IP_OR_HOSTNAME>optional

Deny importing from remote hosts. Optionally specify denied IP addresses and host names, with ports as necessary.

--doc

Type-check code blocks in JSDoc as well as actual code.

--doc-only

Type-check code blocks in JSDoc and Markdown only.

--env-file<FILE>optional

Load environment variables from local file Only the first environment variable with a given key is used. Existing process environment variables are not overwritten, so if variables with the same names already exist in the environment, their values will be preserved. Where multiple declarations for the same environment variable exist in your .env file, the first one encountered is applied. This is determined by the order of the files you pass as arguments.

--minimum-dependency-age<minimum-dependency-age>

(Unstable) The age in minutes, ISO-8601 duration or RFC3339 absolute timestamp (e.g. '120' for two hours, 'P2D' for two days, '2025-09-16' for cutoff date, '2025-09-16T12:00:00+00:00' for cutoff time, '0' to disable).

--no-code-cache

Disable V8 code cache feature.

--no-config

Disable automatic loading of the configuration file.

--v8-flags<V8_FLAGS>optional

To see a list of all available flags use --v8-flags=--help Flags can also be set via the DENO_V8_FLAGS environment variable. Any flags set with this flag are appended after the DENO_V8_FLAGS environment variable.

Desktop options

--desktop

Type-check using the type definitions for deno desktop.

File watching options

--no-clear-screen

Do not clear terminal screen when under watch mode.

--watch

Watch for file changes and restart process automatically. Only local files from entry point module graph are watched.

--watch-exclude<FILES>optional

Exclude provided files/patterns from watch mode.