@dojo/shim

@dojo/shim

This package provides functional shims for ECMAScript, access to the Typescript helpers, and a quick way to include the polyfills needed to run Dojo 2 in the browser.

It is targeted at providing function shims for ECMAScript 6 and beyond targeted at ECMAScript 5. It is different other solutions of shimming or polyfilling functionality, in that it does not provide the functionality via augmenting the built in classes in the global namespace.

There are two exceptions to this. One is the Promise object, which needs to be globally available for async/await operations. The other exception is the Symbol functionality, in that the well-known symbols need to be located off of the global Symbol object in order to ensure that the correct symbol is referenced.

WARNING This is beta software. While we do not anticipate significant changes to the API at this stage, we may feel the need to do so. This is not yet production ready, so you should use at your own risk.

Usage

To use @dojo/shim, install the package along with its required peer dependencies:

npm install @dojo/shim

# peer dependencies
npm install @dojo/has

Include the module in your project to load the global shims and Typescript helpers.

import '@dojo/shim';

Since the main module loads the Typescript helpers, you'll want to turn off helper generation in your project. Add the following option to your tsconfig.json.

{
	"compilerOptions": {
		"noEmitHelpers": true
	}
}

If you are using Dojo 2 in the browser, you will want to load the browser polyfills. These are available by simply importing the @dojo/shim/browser module.

// load polyfills for features used by Dojo 2
import '@dojo/shim/browser';

Note: Other Dojo 2 packages will include these dependencies. You only need to worry about this if you are using this package stand alone.

Features

Many of the features in this package will fallback to a native implementation if one is available.

• Array
• Data Structures
  • Map
  • Set
  • WeakMap
• Iterators
• Math
• Number
• Object
• Observables
• Promises
• String
• Symbols

Array Methods

@dojo/shim/array provides implementations of many array utilities.

Data Structures

Map

The @dojo/shim/Map class is an implementation of the ES2015 Map specification without iterators for use in older browsers.

Set

The @dojo/shim/Set class is an implementation of the ES2015 Set specification. A Set is used to a collection of unique values.

import Set from '@dojo/shim/Set';

const values = new Set<string>();
values.add('one');
values.add('two');
values.add('one');

values.forEach((value) => {
    console.log(value);
});

// output:
// one
// two

WeakMap

The @dojo/shim/WeakMap class is an implementation of the ES2015 WeakMap specification without iterators for use in older browsers. The main difference between WeakMap and Map is that WeakMap's keys can only be objects and that the store has a weak reference to the key/value pair. This allows for the garbage collector to remove pairs.

Look at Map for more information on how to use WeakMap.

Iterators

The @dojo/shim/iterator module is an implementation of the ES2015 Iterator specification.

Math

The @dojo/shim/math module provides implementations for many math methods.

Number

The dojo/shim/number module provides implementations for several Number methods.

• isNaN
• isFinite
• isInteger
• isSafeInteger

Object

The dojo/shim/object provides implementations of Object methods.

• is
• getOwnPropertySymbols
• getOwnPropertyNames
• getOwnPropertyDescriptor
• values
• entries

Observables

The @dojo/shim/Observable class is an implementation of the proposed Observable specification. Observables are further extended in @dojo/core/Observable.

Promises

@dojo/shim/Promise is an implementation of the ES2015 Promise specification.

String

The @dojo/shim/string module contains String methods.

Symbols

@dojo/shim/Symbol provides an implementation of the ES2015 Symbol specification for environments that do not natively support Symbol.

How do I contribute?

We appreciate your interest! Please see the Dojo 2 Meta Repository for the Contributing Guidelines.

Code Style

This repository uses prettier for code styling rules and formatting. A pre-commit hook is installed automatically and configured to run prettier against all staged files as per the configuration in the projects package.json.

An additional npm script to run prettier (with write set to true) against all src and test project files is available by running:

npm run prettier

Installation

To start working with this package, clone the repository and run npm install.

In order to build the project run grunt dev or grunt dist.

Testing

Test cases MUST be written using Intern using the Object test interface and Assert assertion interface.

90% branch coverage MUST be provided for all code submitted to this repository, as reported by istanbul’s combined coverage results for all supported platforms.

To test locally in node run:

grunt test

To test against browsers with a local selenium server run:

grunt test:local

To test against BrowserStack or Sauce Labs run:

grunt test:browserstack

or

grunt test:saucelabs

Licensing information

© JS Foundation & contributors. New BSD license.