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Ion-JS Library

Amazon Ion JavaScript

An implementation of Amazon Ion for JavaScript written in TypeScript.

NPM Version License Travis CI Status Documentation

This package is designed to work with Node JS major versions 8, 10, and 12. While this library should be usable within browsers that support ES5+, please note that it is not currently being tested in any browser environments.

Getting Started

You can use this library either as a Node.js module or inside an HTML page.


  1. Add ion-js and jsbi to your dependencies using npm

     npm install --save ion-js jsbi
  2. Use the library to read/write Ion data. Here is an example that reads Ion data from a JavaScript string:

     let ion = require("ion-js");
     // Reading
     let ionData = '{ greeting: "Hello", name: "Ion" }';
     let value = ion.load(ionData);
     console.log(value.greeting + ", " + value.name + "!");
     // Writing
     let ionText = ion.dumpText(value);
     console.log("Serialized Ion: " + ionText);

    For more examples, see the Ion DOM README.

Try it yourself.

Note: if your package's public interface exposes part of this library, this library should be specified as a peer dependency in your package's package.json file. Otherwise, packages that depend on your package and this library may experience unexpected behavior, as two installations of this library (even if the same version) are not designed or tested to behave correctly.

Web Browser

You can include the Ion-js bundle (ES5 compatible) using the URLs

These will create and initialize window.ion which has the same exact API as our npm package. Here is an example

  <meta charset="UTF-8"/>
  <script src="scripts/ion-bundle.min.js"></script>

  <!-- more HTML/JS code that can now use `window.ion` to create/write Ion -->


TypeDoc generated documentation can be found at here. Please note that anything not documented in the the API documentation is not supported for public use and is subject to change in any version.

Git Setup

This repository contains a git submodule called ion-tests, which holds test data used by ion-js's unit tests.

The easiest way to clone the ion-js repository and initialize its ion-tests submodule is to run the following command.

$ git clone --recursive https://github.com/amzn/ion-js.git ion-js

Alternatively, the submodule may be initialized independently from the clone by running the following commands.

$ git submodule init
$ git submodule update


Use npm to setup the dependencies. In the project directory you can run the following:

$ npm install

Building the package can be done with the release script (which runs the tests).

$ npm run release

Tests can be run using npm as well

$ npm test

This package uses Grunt for its build tasks. For convenience, you may want to install this globally:

$ npm -g install grunt-cli
$ grunt release

Or you could use the locally installed Grunt:

$ ./node_modules/.bin/grunt release

Build Output

The build above will compile the library into the dist directory. This directory has subdirectories of the form <module type>/<target ES version>. In general, we target ES6 and rely on polyfills to support earlier versions.

  • dist/es6/es6 - Targets the ES6 module system and ES6
  • dist/commonjs/es6 - Targets the CommonJS module system and ES6
  • dist/amd/es6 - Targets the AMD module system and ES6

A distribution using browserify and babelify creates a browser friendly polyfilled distribution targeting ES5: at dist/browser/js/ion-bundle.js.

Ion Specification Support

Types IonText IonBinary Limitations
null yes yes none
bool yes yes none
int yes yes underscores, binary digits
float yes yes underscores
decimal yes yes none
timestamp yes yes none
string yes yes none
symbol yes yes $0, symbol tokens
blob yes yes none
clob yes yes none
struct yes yes none
list yes yes none
sexp yes yes none
annotations yes yes none
local symbol tables yes yes none
shared symbol tables no no none


  • test/iontests.ts defines multiple skipList variables referencing test vectors that are not expected to work at this time.




This library is licensed under Apache License version 2.0


For more information about Ion or its other impleemntation, please see: