📃 May 2018 release notes

Newly available

The following features are newly available:

Array iterators: Arrays are iterable with the for … of statement and enumerable with the methods entries(), keys(), and values().
JavaScript modules: JavaScript modules allow code to be organized into reusable units. Modules use import to load other modules and export to declare what is available to import from other modules. In HTML, modules are loaded with <script type="module">.

The following features are now widely available:

initial: The initial keyword resets any CSS property to its initial value as defined by the specification. For example, the initial value of the display property is inline, regardless of the element being styled. Not to be confused with revert, which resets to the user or browser default style.
<template>: The <template> HTML element holds HTML fragments which you can clone and insert into the document using JavaScript.

The following features are now available in Chrome:

BigInt: The BigInt JavaScript type represents integers of any size, including integers too large for the primitive Number type.
BigInt64Array: The BigInt64Array and BigUint64Array typed arrays represent 64-bit integers, signed and unsigned respectively.
Customized built-in elements: Customized built-in elements are HTML elements that extend built-in elements using the is attribute, to add new behaviors that you define.
Gyroscope: The Gyroscope API reads the angular velocity of a device in three dimensions.
Network Information: The navigator.connection API provides information about the network connection a device is using and fires events when the connection type changes.
Orientation Sensor: The AbsoluteOrientationSensor and RelativeOrientationSensor APIs describe the physical orientation of a device in three-dimensional space, either in relation to the Earth's coordinate system or in relation to the device's own orientation, respectively.
Web authentication: The web authentication API allows you to create public key-based credentials and use them for authentication, such as when signing in. Also known as WebAuthn.

The following features are now available in Chrome Android:

BigInt: The BigInt JavaScript type represents integers of any size, including integers too large for the primitive Number type.
BigInt64Array: The BigInt64Array and BigUint64Array typed arrays represent 64-bit integers, signed and unsigned respectively.
Customized built-in elements: Customized built-in elements are HTML elements that extend built-in elements using the is attribute, to add new behaviors that you define.
Gyroscope: The Gyroscope API reads the angular velocity of a device in three dimensions.
Network Information: The navigator.connection API provides information about the network connection a device is using and fires events when the connection type changes.
Orientation Sensor: The AbsoluteOrientationSensor and RelativeOrientationSensor APIs describe the physical orientation of a device in three-dimensional space, either in relation to the Earth's coordinate system or in relation to the device's own orientation, respectively.

The following features are now available in Firefox:

Credential management: The navigator.credentials API provides generic storage for authentication credentials. Other credential APIs represent specific kinds of credentials, such as password or public key credentials, that the credential management API stores.
Web authentication: The web authentication API allows you to create public key-based credentials and use them for authentication, such as when signing in. Also known as WebAuthn.

The following features are now available in Firefox for Android:

Credential management: The navigator.credentials API provides generic storage for authentication credentials. Other credential APIs represent specific kinds of credentials, such as password or public key credentials, that the credential management API stores.