NamedBits

namedbits is a TypeScript/JavaScript library implementing a bit field, with named bits for easier access.

Installation

Install namedbits into an existing project:

# npm
npm install --save namedbits

Usage

import { NamedBits } from "namedbits";

// create new bit field
const bits = new NamedBits(["aa", "bb", "cc"] as const);

// set a bit
bits.set("bb");

// get a bit
bits.get("bb");
// true

// get the bit field as a number
bits.toNumber();
// 2

// convert to JSON
JSON.stringify({ bits });
// '{"bits":"2"}'

// convert to JSON as an array
bits.setOptions({json: "array"});
JSON.stringify({ bits });
// '{"bits":["bb"]}'

// try to use an invalid field name
// this relies on "as const" when creating the bit field
bits.set("omega");
// <repl>.ts:10:10 - error TS2345: Argument of type '"omega"' is not assignable to parameter of type '"aa" | "bb" | "cc"'.
// 
// 10 bits.set("omega");
//             ~~~~~~~

Documentation

new NamedBits(names, options)

Creates a new bit field

Params

• names - array of strings
  • The names of bits, starting at the first. Pass a constant array (e.g.: ["aa", "bb", "cc"] as const ) to have the names be type checked.
• options - object
  • see NamedBits#setOptions(options)

NamedBits#get(name)

Returns the value of a bit identified by the name

NamedBits#set(name, value = true)

Sets the value of a bit, to true by default

NamedBits#clear(name)

Clears the value of a bit. Identical to .set(name, false)

NamedBits#toggle(name)

Toggles the value of a bit

NamedBits#setAll()

Sets all bits to true

NamedBits#clearAll()

Sets all bits to false

NamedBits#setOptions(options)

Customizes bit field's behavior Params

• options - object
  • options.json - "string_list" | "string_bigint" | "array" | "number"
    • Changes the way the bit field is serialized by JSON.stringify()
    • string_list - list of set field names, separated by a comma
    • string_bigint - value of the bit field as a bigint, converted to a string
    • array - JSON array of set bit names
    • number - value of the bit field as a number
      • Note, this will throw an exception if there are more than 53 bits, since JavaScript's number type cannot safely handle integers larger than 2^53.

NamedBits#toArray()

Returns a list set bit names as an array of strings

NamedBits#toNumber()

Returns the value of the bit field as a number.

Note, this will throw an exception if there are more than 53 bits, since JavaScript's number type cannot safely handle integers larger than 2^53.

NamedBits#toBigInt()

Returns the value of the bit field as a bignum

NamedBits#toString()

Returns a list of set bit names separated by a comma

NamedBits#toJSON()

Helper method for JSON.stringify(), configured by options.json

License

MIT