HTML Web APIs Introduction

A Web API is a developer's dream. It can extend what the browser can do, greatly simplify complex functions, and provide easy syntax for complex code.

API stands for Application Programming Interface. An API is an interface with a set of functions and subroutines that let programmers reach specific features or data of an application, operating system, or other service. A Web API is an application programming interface for the web.

All browsers have a set of built-in Web APIs for complex operations and for reaching data. Some of the main HTML5 APIs are: the Geolocation API, used to get the user's current location (latitude and longitude); the Drag and Drop API, which enables drag-and-drop features; the Web Storage API, which lets browsers store key/value pairs more intuitively than cookies; the Web Workers API, which lets JavaScript run in the background without slowing the page; the Server-Sent Events API, which lets a page automatically receive updates from a server; and the Canvas API, which lets you draw graphics on the fly with JavaScript.

When using an HTML API, you should always: check browser capability, making sure the target browsers support the API and adding a script or message for those that do not; add robust error handling for cases where the API may not work as expected; and request user permission when the API reaches sensitive data, like the Geolocation API accessing the user's position, by asking for consent first.

Third-party APIs are not built into the browser, so to use them you download the code from the web. Examples include the YouTube API (to show videos on a site), the Twitter API (to show tweets), and the Facebook API (to show Facebook information).