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Deno Namespace APIs
The global Deno namespace contains APIs that are not web standard, including APIs for reading from files, opening TCP sockets, serving HTTP, and executing subprocesses, etc.
For a full list of Deno Built-in APIs, see the reference. Below we highlight some of the most important.
File System Jump to heading
The Deno runtime comes with various functions for working with files and directories. You will need to use --allow-read and --allow-write permissions to gain access to the file system.
Refer to the links below for code examples of how to use the file system functions.
- Reading files in several different ways
- Reading files in streams
- Reading a text file (
Deno.readTextFile
) - Writing a text file (
Deno.writeTextFile
)
Network Jump to heading
The Deno runtime comes with built-in functions for dealing with connections to network ports.
Refer to the links below for code examples for common functions.
- Connect to the hostname and port (
Deno.connect
) - Announcing on the local transport address (
Deno.listen
)
Subprocesses Jump to heading
The Deno runtime comes with built-in functions for spinning up subprocesses.
Refer to the links below for code samples of how to create a subprocess.
Errors Jump to heading
The Deno runtime comes with 20 error classes that can be raised in response to a number of conditions.
Some examples are:
Deno.errors.NotFound;
Deno.errors.WriteZero;
They can be used as below:
try {
const file = await Deno.open("./some/file.txt");
} catch (error) {
if (error instanceof Deno.errors.NotFound) {
console.error("the file was not found");
} else {
// otherwise re-throw
throw error;
}
}