Skip to main content
Module

std/encoding/README.md

Deno standard library
denoland/deno
Go to Latest
File

encoding

Helper module for dealing with external data structures.

Binary

Implements equivalent methods to Go’s encoding/binary package.

Available Functions:

sizeof(dataType: RawTypes): number
getNBytes(r: Deno.Reader, n: number): Promise<Uint8Array>
varnum(b: Uint8Array, o: VarnumOptions = {}): number | null
varbig(b: Uint8Array, o: VarbigOptions = {}): bigint | null
putVarnum(b: Uint8Array, x: number, o: VarnumOptions = {}): number
putVarbig(b: Uint8Array, x: bigint, o: VarbigOptions = {}): number
readVarnum(r: Deno.Reader, o: VarnumOptions = {}): Promise<number>
readVarbig(r: Deno.Reader, o: VarbigOptions = {}): Promise<bigint>
writeVarnum(w: Deno.Writer, x: number, o: VarnumOptions = {}): Promise<number>
writeVarbig(w: Deno.Writer, x: bigint, o: VarbigOptions = {}): Promise<number>

CSV

API

readMatrix(reader: BufReader, opt: ReadOptions = { comma: ",", trimLeadingSpace: false, lazyQuotes: false }): Promise<string[][]>

Parse the CSV from the reader with the options provided and return string[][].

parse(input: string | BufReader, opt: ParseOptions = { header: false }): Promise<unknown[]>:

Parse the CSV string/buffer with the options provided. The result of this function is as follows:

  • If you don’t provide both opt.header and opt.parse, it returns string[][].
  • If you provide opt.header but not opt.parse, it returns object[].
  • If you provide opt.parse, it returns an array where each element is the value returned from opt.parse.
ParseOptions
  • header: boolean | string[] | HeaderOptions[];: If a boolean is provided, the first line will be used as Header definitions. If string[] or HeaderOptions[] those names will be used for header definition.
  • parse?: (input: unknown) => unknown;: Parse function for the row, which will be executed after parsing of all columns. Therefore if you don’t provide header and parse function with headers, input will be string[].
HeaderOptions
  • name: string;: Name of the header to be used as property.
  • parse?: (input: string) => unknown;: Parse function for the column. This is executed on each entry of the header. This can be combined with the Parse function of the rows.
ReadOptions
  • comma?: string;: Character which separates values. Default: ','
  • comment?: string;: Character to start a comment. Default: '#'
  • trimLeadingSpace?: boolean;: Flag to trim the leading space of the value. Default: false
  • lazyQuotes?: boolean;: Allow unquoted quote in a quoted field or non double quoted quotes in quoted field. Default: ‘false`
  • fieldsPerRecord?: Enabling the check of fields for each row. If == 0, first row is used as referral for the number of fields.

Usage

import { parse } from "https://deno.land/std/encoding/csv.ts";
const string = "a,b,c\nd,e,f";

console.log(
  await parse(string, {
    header: false,
  }),
);
// output:
// [["a", "b", "c"], ["d", "e", "f"]]

TOML

This module parse TOML files. It follows as much as possible the TOML specs. Be sure to read the supported types as not every specs is supported at the moment and the handling in TypeScript side is a bit different.

Supported types and handling

:exclamation: Supported with warnings see Warning.

⚠️ Warning

String
  • Regex : Due to the spec, there is no flag to detect regex properly in a TOML declaration. So the regex is stored as string.
Integer

For Binary / Octal / Hexadecimal numbers, they are stored as string to be not interpreted as Decimal.

Local Time

Because local time does not exist in JavaScript, the local time is stored as a string.

Inline Table

Inline tables are supported. See below:

animal = { type = { name = "pug" } }
## Output { animal: { type: { name: "pug" } } }
animal = { type.name = "pug" }
## Output { animal: { type : { name : "pug" } }
animal.as.leaders = "tosin"
## Output { animal: { as: { leaders: "tosin" } } }
"tosin.abasi" = "guitarist"
## Output { tosin.abasi: "guitarist" }
Array of Tables

At the moment only simple declarations like below are supported:

[[bin]]
name = "deno"
path = "cli/main.rs"

[[bin]]
name = "deno_core"
path = "src/foo.rs"

[[nib]]
name = "node"
path = "not_found"

will output:

{
  "bin": [
    { "name": "deno", "path": "cli/main.rs" },
    { "name": "deno_core", "path": "src/foo.rs" }
  ],
  "nib": [{ "name": "node", "path": "not_found" }]
}

Basic usage

import { parse, stringify } from "https://deno.land/std/encoding/toml.ts";
const obj = {
  bin: [
    { name: "deno", path: "cli/main.rs" },
    { name: "deno_core", path: "src/foo.rs" },
  ],
  nib: [{ name: "node", path: "not_found" }],
};
const tomlString = stringify(obj);
console.log(tomlString);

// =>
// [[bin]]
// name = "deno"
// path = "cli/main.rs"

// [[bin]]
// name = "deno_core"
// path = "src/foo.rs"

// [[nib]]
// name = "node"
// path = "not_found"

const tomlObject = parse(tomlString);
console.log(tomlObject);

// =>
// {
//     bin: [
//       { name: "deno", path: "cli/main.rs" },
//       { name: "deno_core", path: "src/foo.rs" }
//     ],
//     nib: [ { name: "node", path: "not_found" } ]
//   }

YAML

YAML parser / dumper for Deno

Heavily inspired from [js-yaml]

Basic usage

parse parses the yaml string, and stringify dumps the given object to YAML string.

import { parse, stringify } from "https://deno.land/std/encoding/yaml.ts";

const data = parse(`
foo: bar
baz:
  - qux
  - quux
`);
console.log(data);
// => { foo: "bar", baz: [ "qux", "quux" ] }

const yaml = stringify({ foo: "bar", baz: ["qux", "quux"] });
console.log(yaml);
// =>
// foo: bar
// baz:
//   - qux
//   - quux

If your YAML contains multiple documents in it, you can use parseAll for handling it.

import { parseAll } from "https://deno.land/std/encoding/yaml.ts";

const data = parseAll(`
---
id: 1
name: Alice
---
id: 2
name: Bob
---
id: 3
name: Eve
`);
console.log(data);
// => [ { id: 1, name: "Alice" }, { id: 2, name: "Bob" }, { id: 3, name: "Eve" } ]

API

parse(str: string, opts?: ParserOption): unknown

Parses the YAML string with a single document.

parseAll(str: string, iterator?: Function, opts?: ParserOption): unknown

Parses the YAML string with multiple documents. If the iterator is given, it’s applied to every document instead of returning the array of parsed objects.

stringify(obj: object, opts?: DumpOption): string

Serializes object as a YAML document.

⚠️ Limitations

  • binary type is currently not stable
  • function, regexp, and undefined type are currently not supported

More example

See https://github.com/nodeca/js-yaml.

base32

RFC4648 base32 encoder/decoder for Deno

Basic usage

encode encodes a Uint8Array to RFC4648 base32 representation, and decode decodes the given RFC4648 base32 representation to a Uint8Array.

import { encode, decode } from "https://deno.land/std/encoding/base32.ts";

const b32Repr = "RC2E6GA=";

const binaryData = decode(b32Repr);
console.log(binaryData);
// => Uint8Array [ 136, 180, 79, 24 ]

console.log(encode(binaryData));
// => RC2E6GA=

ascii85

Ascii85/base85 encoder and decoder with support for multiple standards

Basic usage

encode encodes a Uint8Array to a ascii85 representation, and decode decodes the given ascii85 representation to a Uint8Array.

import { encode, decode } from "https://deno.land/std/encoding/ascii85.ts";

const a85Repr = "LpTqp";

const binaryData = decode(a85Repr);
console.log(binaryData);
// => Uint8Array [ 136, 180, 79, 24 ]

console.log(encode(binaryData));
// => LpTqp

Specifying a standard and delimeter

By default all functions are using the most popular Adobe version of ascii85 and not adding any delimeter. However, there are three more standards supported - btoa (different delimeter and additional compression of 4 bytes equal to 32), Z85 and RFC 1924. It’s possible to use a different encoding by specifying it in options object as a second parameter.

Similarly, it’s possible to make encode add a delimeter (<~ and ~> for Adobe, xbtoa Begin and xbtoa End with newlines between the delimeters and encoded data for btoa. Checksums for btoa are not supported. Delimeters are not supported by other encodings.)

encoding examples:

import { encode, decode } from "https://deno.land/std/encoding/ascii85.ts";
const binaryData = new Uint8Array([136, 180, 79, 24]);
console.log(encode(binaryData));
// => LpTqp
console.log(encode(binaryData, { standard: "Adobe", delimeter: true }));
// => <~LpTqp~>
console.log(encode(binaryData, { standard: "btoa", delimeter: true }));
/* => xbtoa Begin
LpTqp
xbtoa End */
console.log(encode(binaryData, { standard: "RFC 1924" }));
// => h_p`_
console.log(encode(binaryData, { standard: "Z85" }));
// => H{P}{