Deno

A set of error constructors that are raised by Deno APIs.

The Deno abstraction for reading and writing files.

Returns the script arguments to the program. If for example we run a program:

Build related information.

A symbol which can be used as a key for a custom method which will be called when Deno.inspect() is called, or when the object is logged to the console.

The URL of the entrypoint module entered from the command-line.

Reflects the NO_COLOR environment variable at program start.

Deno's permission management API.

The current process id of the runtime.

The pid of the current process's parent.

A handle for stderr.

A handle for stdin.

A handle for stdout.

Version related information.

Registers the given function as a listener of the given signal event.

Change the current working directory to the specified path.

Changes the permission of a specific file/directory of specified path. Ignores the process's umask.

Synchronously changes the permission of a specific file/directory of specified path. Ignores the process's umask.

Change owner of a regular file or directory. This functionality is not available on Windows.

Synchronously change owner of a regular file or directory. This functionality is not available on Windows.

Close the given resource ID (rid) which has been previously opened, such as via opening or creating a file. Closing a file when you are finished with it is important to avoid leaking resources.

Connects to the hostname (default is "127.0.0.1") and port on the named transport (default is "tcp"), and resolves to the connection (Conn).

Establishes a secure connection over TLS (transport layer security) using an optional cert file, hostname (default is "127.0.0.1") and port. The cert file is optional and if not included Mozilla's root certificates will be used (see also https://github.com/ctz/webpki-roots for specifics)

Copies from src to dst until either EOF (null) is read from src or an error occurs. It resolves to the number of bytes copied or rejects with the first error encountered while copying.

Copies the contents and permissions of one file to another specified path, by default creating a new file if needed, else overwriting. Fails if target path is a directory or is unwritable.

Synchronously copies the contents and permissions of one file to another specified path, by default creating a new file if needed, else overwriting. Fails if target path is a directory or is unwritable.

Creates a file if none exists or truncates an existing file and resolves to an instance of Deno.FsFile.

Creates a file if none exists or truncates an existing file and returns an instance of Deno.FsFile.

Return a string representing the current working directory.

Returns the path to the current deno executable.

Exit the Deno process with optional exit code. If no exit code is supplied then Deno will exit with return code of 0.

Flushes any pending data operations of the given file stream to disk.

const file = await Deno.open("my_file.txt", { read: true, write: true, create: true });
await Deno.write(file.rid, new TextEncoder().encode("Hello World"));
await Deno.fdatasync(file.rid);
console.log(new TextDecoder().decode(await Deno.readFile("my_file.txt"))); // Hello World

Returns a Deno.FileInfo for the given file stream.

Synchronously returns a Deno.FileInfo for the given file stream.

Flushes any pending data and metadata operations of the given file stream to disk.

const file = await Deno.open("my_file.txt", { read: true, write: true, create: true });
await Deno.write(file.rid, new TextEncoder().encode("Hello World"));
await Deno.ftruncate(file.rid, 1);
await Deno.fsync(file.rid);
console.log(new TextDecoder().decode(await Deno.readFile("my_file.txt"))); // H

Synchronously flushes any pending data and metadata operations of the given file stream to disk.

const file = Deno.openSync("my_file.txt", { read: true, write: true, create: true });
Deno.writeSync(file.rid, new TextEncoder().encode("Hello World"));
Deno.ftruncateSync(file.rid, 1);
Deno.fsyncSync(file.rid);
console.log(new TextDecoder().decode(Deno.readFileSync("my_file.txt"))); // H

Truncates or extends the specified file stream, to reach the specified len.

Synchronously truncates or extends the specified file stream, to reach the specified len.

Converts the input into a string that has the same format as printed by console.log().

Check if a given resource id (rid) is a TTY.

Turns a Reader, r, into an async iterator.

Turns a ReaderSync, r, into an iterator.

Send a signal to process under given pid.

Creates newpath as a hard link to oldpath.

Synchronously creates newpath as a hard link to oldpath.

Listen announces on the local transport address.

Listen announces on the local transport address over TLS (transport layer security).

Resolves to a Deno.FileInfo for the specified path. If path is a symlink, information for the symlink will be returned instead of what it points to.

Synchronously returns a Deno.FileInfo for the specified path. If path is a symlink, information for the symlink will be returned instead of what it points to..

Creates a new temporary directory in the default directory for temporary files, unless dir is specified. Other optional options include prefixing and suffixing the directory name with prefix and suffix respectively.

Synchronously creates a new temporary directory in the default directory for temporary files, unless dir is specified. Other optional options include prefixing and suffixing the directory name with prefix and suffix respectively.

Creates a new temporary file in the default directory for temporary files, unless dir is specified. Other optional options include prefixing and suffixing the directory name with prefix and suffix respectively.

Synchronously creates a new temporary file in the default directory for temporary files, unless dir is specified. Other optional options include prefixing and suffixing the directory name with prefix and suffix respectively.

Returns an object describing the memory usage of the Deno process measured in bytes.

Receive metrics from the privileged side of Deno. This is primarily used in the development of Deno. 'Ops', also called 'bindings', are the go-between between Deno JavaScript and Deno Rust.

Creates a new directory with the specified path.

Synchronously creates a new directory with the specified path.

Open a file and resolve to an instance of Deno.FsFile. The file does not need to previously exist if using the create or createNew open options. It is the callers responsibility to close the file when finished with it.

Synchronously open a file and return an instance of Deno.FsFile. The file does not need to previously exist if using the create or createNew open options. It is the callers responsibility to close the file when finished with it.

Read from a resource ID (rid) into an array buffer (buffer).

Read Reader r until EOF (null) and resolve to the content as Uint8Array`.

Synchronously reads Reader r until EOF (null) and returns the content as Uint8Array.

Reads the directory given by path and returns an async iterable of Deno.DirEntry.

Synchronously reads the directory given by path and returns an iterable of Deno.DirEntry.

Reads and resolves to the entire contents of a file as an array of bytes. TextDecoder can be used to transform the bytes to string if required. Reading a directory returns an empty data array.

Synchronously reads and returns the entire contents of a file as an array of bytes. TextDecoder can be used to transform the bytes to string if required. Reading a directory returns an empty data array.

Resolves to the full path destination of the named symbolic link.

Returns the full path destination of the named symbolic link.

Synchronously read from a resource ID (rid) into an array buffer (buffer).

Asynchronously reads and returns the entire contents of a file as utf8 encoded string. Reading a directory throws an error.

Synchronously reads and returns the entire contents of a file as utf8 encoded string. Reading a directory throws an error.

Resolves to the absolute normalized path, with symbolic links resolved.

Returns absolute normalized path, with symbolic links resolved.

Removes the named file or directory.

Removes the given signal listener that has been registered with Deno.addSignalListener.

Synchronously removes the named file or directory.

Renames (moves) oldpath to newpath. Paths may be files or directories. If newpath already exists and is not a directory, rename() replaces it. OS-specific restrictions may apply when oldpath and newpath are in different directories.

Synchronously renames (moves) oldpath to newpath. Paths may be files or directories. If newpath already exists and is not a directory, renameSync() replaces it. OS-specific restrictions may apply when oldpath and newpath are in different directories.

Returns a map of open resource ids (rid) along with their string representations. This is an internal API and as such resource representation has any type; that means it can change any time.

Spawns new subprocess. RunOptions must contain at a minimum the opt.cmd, an array of program arguments, the first of which is the binary.

Seek a resource ID (rid) to the given offset under mode given by whence. The call resolves to the new position within the resource (bytes from the start).

Synchronously seek a resource ID (rid) to the given offset under mode given by whence. The new position within the resource (bytes from the start) is returned.

Services HTTP requests given a TCP or TLS socket.

Shutdown socket send operations.

Start TLS handshake from an existing connection using an optional list of CA certificates, and hostname (default is "127.0.0.1"). Specifying CA certs is optional. By default the configured root certificates are used. Using this function requires that the other end of the connection is prepared for a TLS handshake.

Resolves to a Deno.FileInfo for the specified path. Will always follow symlinks.

Synchronously returns a Deno.FileInfo for the specified path. Will always follow symlinks.

Creates newpath as a symbolic link to oldpath.

Creates newpath as a symbolic link to oldpath.

Register a test which will be run when deno test is used on the command line and the containing module looks like a test module. fn can be async if required.

import {assert, fail, assertEquals} from "https://deno.land/std/testing/asserts.ts";

Truncates or extends the specified file, to reach the specified len. If len is not specified then the entire file contents are truncated.

Synchronously truncates or extends the specified file, to reach the specified len. If len is not specified then the entire file contents are truncated.

Used to upgrade an incoming HTTP request to a WebSocket.

Watch for file system events against one or more paths, which can be files or directories. These paths must exist already. One user action (e.g. touch test.file) can generate multiple file system events. Likewise, one user action can result in multiple file paths in one event (e.g. mv old_name.txt new_name.txt). Recursive option is true by default and, for directories, will watch the specified directory and all sub directories. Note that the exact ordering of the events can vary between operating systems.

Write to the resource ID (rid) the contents of the array buffer (data).

Write all the content of the array buffer (arr) to the writer (w).

Synchronously write all the content of the array buffer (arr) to the writer (w).

Write data to the given path, by default creating a new file if needed, else overwriting.

Synchronously write data to the given path, by default creating a new file if needed, else overwriting.

Synchronously write to the resource ID (rid) the contents of the array buffer (data).

Asynchronously write string data to the given path, by default creating a new file if needed, else overwriting.

Synchronously write string data to the given path, by default creating a new file if needed, else overwriting.

If resolveDns is called with "CAA" record type specified, it will return an array of this interface.

A FileInfo describes a file and is returned by stat, lstat, statSync, lstatSync.

FsWatcher is returned by Deno.watchFs function when you start watching the file system. You can iterate over this interface to get the file system events, and also you can stop watching the file system by calling .close() method.

A generic network listener for stream-oriented protocols.

If resolveDns is called with "MX" record type specified, it will return an array of this interface.

If resolveDns is called with "NAPTR" record type specified, it will return an array of this interface.

If resolveDns is called with "SOA" record type specified, it will return an array of this interface.

If resolveDns is called with "SRV" record type specified, it will return an array of this interface.

Specialized listener that accepts TLS connections.

Options for writing to a file.

Additional information for FsEvent objects with the "other" kind.

Permission descriptors which define a permission and can be queried, requested, or revoked.

The name of a "powerful feature" which needs permission.

The current status of the permission.

The type of the resource record. Only the listed types are supported currently.