snyk npm package size

Formats message strings with number, date, plural, and select placeholders to create localized messages.

  • Small. Between 700 bytes and 1.3 kilobytes (minified and gzipped). Zero dependencies.
  • Fast. Does absolute minimum amount of computations necessary. View benchmarks.
  • Tree Shakable. Includes separate global transformers config that can be omitted.
  • Pipe syntax. Transformer functions can customized and chained.
  • View framework support. Use React/Preact etc. components as transformers.
  • It has good TypeScript support.

import { MessagePipe } from 'messagepipe'

const msg = MessagePipe().compile('Hello {planet}!')

msg({ planet: 'Mars' }) // => "Hello Mars!"

live demo

import { MessagePipe } from 'messagepipe'

const { compile } = MessagePipe({
  reverse: (val) => val.split('').reverse().join(''),
  capitalize: (val) => val[0].toUpperCase() + val.slice(1).toLowerCase(),

const msg = compile('Hello {planet | reverse | capitalize}!')

msg({ planet: 'Mars' }) // => "Hello Sram!"

live demo


npm install messagepipe


Core concepts

          |     ┌-argument name
          |     |     ┌-argument value
          ├--┐  ├---┐ ├-┐

  {name | json, space:101}

  |├--┘   ├-------------┘
  ||      |     ├-------┘
  ||      |     └-argument
  ||      └-pipe

In one message there can only be one selector, but there can be unlimited number of pipes with unlimited number of arguments in them. It is possible to build dynamic selector (meaning message can be inside it), but it is not possible to build dynamic pipes except for argument values.

So both of these are valid:

  1. "Hello {agents.{index}.fistName}";
  2. "{a} + {b} = {a | sum, sequence:{b}}". (Note: sum is a custom transformer in this case).


Contains everything between { and } that in large includes 1 selector and n pipes.


String value that points to value from given props object e.g.:

  • "{name}" + { name: 'john' } => "john";
  • "{agents[0].name}" + { agents: [{ name: 'john' }] } => "john"


A combination of 1 transformer and n arguments e.g.:

  • "{name | capitalize}";
  • "{name | reverse | capitalize}";
  • "{a | sum, sequence:1, double}" (Note: argument “double” will pass true value to “sum” transformer).


Function that can transform value that is being selected from given props.

Lets define “capitalize” transformer that would uppercase the first letter of any string:

function capitalize(value: string) {
  return value[0].toUpperCase() + value.slice(1).toLowerCase();

To use this transformer define it when initiating MessagePipe and then it will be available to pipes with name “capitalize”:

const msgPipe = MessagePipe({

This would be valid use case for it: "Greetings {name | capitalize}!".


To allow more functionality, we can use arguments, that are passed to transformer function.

function increment(value: number, { by = 1 }: Record<string, any> = {}) {
  return value + by;

We can now use it like this:

  • "{count | increment}" + { count: 1 } => 2;
  • "{count | increment | by:1}" + { count: 1 } => 2;
  • "{count | increment | by:5}" + { count: 1 } => 6.

We can stack any number of arguments separated by , (comma).

Global transformers

There are number of already provided transformers, but they MUST be added to MessagePipe function when initiating. This is by design to help with tree shaking (although they don’t contribute that much to package size, if there are additions in future, that won’t hurt anyone).


function defaultTransformers(): MessagePipeTransformers


Selects what text to show based on incoming value.

const msg = compile('{gender | select, male:"He", female:"She", other:"They"} liked this.')

msg({ gender: 'male' }) // "He liked this"
msg({ gender: 'female' }) // "She liked this"
msg({ }) // "They liked this"


Runs value through JSON.stringify.


function intlTransformers(locale?: string): MessagePipeTransformers


Formats numbers using Intl.NumberFormat. All options are available as arguments in pipes.

const msg = compile('{price | number}')

msg({ price: 123456.789 }) // "123,456.789"

const msg = compile('Price: {price | number, style:"currency", currency:"EUR"}')

msg({ price: 123 }) // "Price: 123,00 €"


Selects correct text to show based on Intl.PluralRules. All options are available as arguments in pipes.

const msg = compile('I have {fruits | plural, one:"1 fruit", other:"# fruits"}')

msg({ fruits: 0 }) // "I have 0 fruits"
msg({ fruits: 1 }) // "I have 1 fruit"
msg({ fruits: 2 }) // "I have 2 fruits"


Formats date using Intl.DateTimeFormat. All options are available as arguments in pipes.

const msg = compile('Todays date {now | date}')

msg({ now: new Date('1977-05-25') }) // "Todays date 25/05/1977"


Formats time using Intl.DateTimeFormat. All options are available as arguments in pipes.

const msg = compile('Currently it is {now | time}')

msg({ now: new Date('1983-05-25 16:42') }) // "Currently it is 16:42:00"



This is the main function that takes in all the transformers that will be available to all the messages.

function MessagePipe(transformers?: MessagePipeTransformers): {
  compileRaw(message: string): (props?: Record<string, any>) => string[]
  compile(message: string): (props?: Record<string, any>) => string

Example usage:

const messagePipe = MessagePipe({
  hello: (value) => `Hello ${value}!`,

Now all the messages that get compiled from messagePipe can use this transformer like so "{name | hello}".


This is where given message gets parsed and prepared for usage. It is very efficient compiler that does only 1 pass and prepares very tiny and performant function from it.

Given this message "Hello {name | capitalize}!", compiler will output this function (a) => "Hello " + capitalize( + "!" and that is the only thing that runs when executing it. No hidden performance penalties.


This is practically the same as compile but instead of it returning one string, it returns array of all of the things as a separate chunks so that this compiler can be used as part of React component for example.

So from the example that was before, the output of that message would be (a) => ["Hello ", capitalize(, "!"].


It is necessary for me that this library is as small and as fast as possible. Since this library compares directly with MessageFormat, I treated both as equal in benchmarks.

Message MessageFormat MessagePipe Improvement
“Wow” 926,368 ops/s 1,847,253 ops/s 2x
“Hello {planet}” 560,131 ops/s 1,024,051 ops/s 1.8x
select transformer 209,513 ops/s 337,226 ops/s 1.6x

Framework integration

Works with React and Preact out of the box. Just swap out compile with compileRaw and good to go. This works because it returns raw array of values that was the output of selectors and transformers.

import { MessagePipe } from 'messagepipe'

function Mention(username) {
  const {href} = useUser(username)

  return <a href={href}>{username}</a>

// We use React/Preact component as a transformer
const { compileRaw } = MessagePipe({ Mention })
const msg = compileRaw('Hello {name | Mention}!')

function App() {
  return <div>{msg({name: 'john'})}</div>
} // => "<div>Hello <a href="...">john</a>!</div>"

Live demo on Stackblitz.

Since we used compileRaw, library would output something like this: ['Hello ', [ReactElement], '!'].

This will work with any kind of framework or custom library.


I was used to messageformat being the go to for this sort of stuff, but it has big flaws in the spec and library maintainers obviously wouldn’t want to deviate from it. So the goal for messagepipe was to create NEW spec that solves all of the issues with it + must be faster & smaller.

One immediate flaw that MessagePipe solves is ability to select nested values and build dynamic messages.


MIT © Marcis Bergmanis


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