Package Exports

utf-helpers
utf-helpers/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (utf-helpers) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

utf helpers

Package containing some low-level helpers to encode/decode strings to UTF-8 and UTF-16 sequences.
Also it has some small helper to encode/decode hex strings.

Zero dependencies. Browser and Node compatible. 1.3Kb minified and gzipped.

Install

npm i utf-helpers
yarn add utf-helpers

Or, just include it to the browser (old school way):

<script src="utf-helpers.min.js"/>
<script>console.log(window.UtfHelpers)</script>

Brief example

import {Utf8, Utf16, HexString} from 'utf-helpers'
// or import just all in one entry point:
// import {UtfHelpers} from 'utf-helpers'

Utf8.stringToU8a('a 🌷') // Uint8Array [97, 32, 240, 159, 140, 183]
Utf8.u8aToString([97, 32, 240, 159, 140, 183]) // "a 🌷"
Utf8.lengthInBytes('a 🌷') // 6

Utf16.stringToU16a('a 🌷') // Uint16Array [97, 32, 55356, 57143]
Utf16.u16aToString([97, 32, 55356, 57143]) // "a 🌷"
Utf16.lengthInBytes('a 🌷') // 4

HexString.toU8a('0x6120f09f8cb7') // Uint8Array [97, 32, 240, 159, 140, 183]
HexString.fromU8a([97, 32, 240, 159, 140, 183])// "0x6120f09f8cb7"

// even super complex strings!
Utf8.lengthInBytes('👨🏼‍👩🏼‍👧🏼‍👧🏼') // 41
Utf16.lengthInBytes('👨🏼‍👩🏼‍👧🏼‍👧🏼') // 19

UTF-8

Example:

Utf8.stringToU8a('abc 🌷 η 人')
// Uint8Array  [97, 98, 99, 32, 240, 159, 140, 183, 32, 206, 183, 32, 228, 186, 186]
Utf8.stringToNumberArray('abc 🌷 η 人')
// [97, 98, 99, 32, 240, 159, 140, 183, 32, 206, 183, 32, 228, 186, 186]
Utf8.stringToHexString('abc 🌷 η 人')
// "0x61626320f09f8cb720ceb720e4baba"

Utf8.u8aToString(Uint8Array.from([97, 98, 99, 32, 240, 159, 140, 183, 32, 206, 183, 32, 228, 186, 186]))
Utf8.numberArrayToString([97, 98, 99, 32, 240, 159, 140, 183, 32, 206, 183, 32, 228, 186, 186])
Utf8.hexStringToString('0x61626320f09f8cb720ceb720e4baba')
// All three give "abc 🌷 η 人"
// Actually `u8aToString` and `numberArrayToString` both can take usual JS array and Uint8Array 

Utf8.lengthInBytes('abc 🌷 η 人') // 15

Methods:

To encode and decode string to Uint8Array:
stringToU8a(str: string): Uint8Array
u8aToString(u8a: Uint8Array): string

To encode and decode string to usual JS array (of numbers):
stringToNumberArray(str: string): number[]
numberArrayToString(arr: number[] | Uint8Array): string

To encode and decode string to hex string:
stringToHexString(str: string): string
hexStringToString(hexString: string): string

Evaluate byte length of the string without encoding: lengthInBytes(str: string): number

UTF-16

Example:

Utf16.stringToNumberArray('abc 🌷 η 人')
// [97, 98, 99, 32, 55356, 57143, 32, 951, 32, 20154]
Utf16.stringToU16a('abc 🌷 η 人')
// Uint16Array [97, 98, 99, 32, 55356, 57143, 32, 951, 32, 20154]

Utf16.u16aToString(Uint16Array.from([97, 98, 99, 32, 55356, 57143, 32, 951, 32, 20154]))
Utf16.numberArrayToString([97, 98, 99, 32, 55356, 57143, 32, 951, 32, 20154])
// Both give "abc 🌷 η 人"
// Actually `u16aToString` and `numberArrayToString` both can take usual JS array and Uint16Array

Utf16.lengthInBytes('abc 🌷 η 人') // 10

Methods

To encode and decode string to Uint16Array:
stringToU16a(str: string): Uint16Array u16aToString(arr: number[] | Uint16Array): string

To encode and decode string to usual JS array (of numbers): stringToNumberArray(str: string): number[] numberArrayToString(arr: number[] | Uint16Array): string

Evaluate byte length of the string without encoding: lengthInBytes(str: string): number

HexString

Example:

HexString.toU8a('0x61626320f09f8cb7')
// Uint8Array [97, 98, 99, 32, 240, 159, 140, 183]
HexString.toArray('0x61626320f09f8cb7')
// [97, 98, 99, 32, 240, 159, 140, 183]

HexString.fromU8a(Uint8Array.from([97, 98, 99, 32, 240, 159, 140, 183]))
HexString.fromArray([97, 98, 99, 32, 240, 159, 140, 183])
// Both give "0x61626320f09f8cb7"


// Also, works with strings without '0x' start:
HexString.toArray('616263') // [97, 98, 99]

// Empty sequences are safe:
HexString.toArray('') // []
HexString.toArray('0x') // []

Methods:

To encode and decode Uint8Array <-> hex string:
fromU8a: (bytes: number[] | Uint8Array) => string
toU8a: (hexString: string) => Uint8Array

To encode and decode JS array (of numbers) <-> hex string:
fromArray: (bytes: number[] | Uint8Array) => string
toArray(hexString: string): number[]