This section provides an overview of the platform support and other useful technical information required to build your app using WebGLA JavaScript API that renders 2D and 3D graphics in a web browser. The Unity WebGL build option allows Unity to publish content as JavaScript programs which use HTML5 technologies and the WebGL rendering API to run Unity content in a web browser. More info
See in Glossary.
Most popular desktop browser versions support the Unity WebGL content, but do note that different browsers offer different level of support. For example, Unity WebGL doesn’t support Mobile devices.
The following features in WebGL builds are either not available or limited due to constraints of the platform itself:
Visual studio doesn’t support debugging Unity WebGL builds. For more information, refer to Debug and troubleshoot WebGL builds.
WebGL builds don’t support the Unity Cache and Caching Scripting API due to restricted access to the filesystem in browsers. Network requests to asset data and AssetBundles are instead cached in the browser cache. Refer to Cache behavior in WebGL.
Threads aren’t supported due to the lack of threading support in JavaScript. This applies to both Unity’s internal use of threads to speed up performance, and to the use of threads in script code and managed dlls. Essentially, anything in the System.Threading namespace isn’t supported.
There are a few networkingThe Unity system that enables multiplayer gaming across a computer network. More info
See in Glossary features that WebGL platform doesn’t support:
Browsers don’t allow direct access to IP sockets for networking due to security concerns. For more information, refer to Web networking.
.NET networking classes within the System.Net namespace aren’t supported.
WebGL platform does not support native socket access because of security limitations within browsers. Therefore, WebGL also doesn’t support features like ICMP ping or UnityEngine.Ping.
There are some limitations in WebGL platform with the WebGL graphics API, which is based on the functionality of the OpenGL ES graphics library. For more information, refer to WebGL graphics.
WebGL builds use a custom backend for Audio based on the WebGL Audio API, but it only supports the basic audio functionality. For more information, refer to Audio in WebGL.
WebGL is an AOT platform, so it doesn’t allow dynamic generation of code using System.Reflection.Emit. This is the same on all other IL2CPPA Unity-developed scripting back-end which you can use as an alternative to Mono when building projects for some platforms. More info
See in Glossary platforms, iOS, and most consoles.
Copy and paste works only within Unity UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary. You can’t copy and paste from the system clipboard, that is, you can’t copy or paste to or from external applications.
Although Unity provides multithreading support for native C/C++ code, the Web platform doesn’t yet support C# multithreading due to limitations of WebAssembly. This means that applications built using the Web platform must run on a single C# thread.
Notes:
The Web platform supports C/C++ multithreading only if you enable Native C/C++ support in the Web Player settingsSettings that let you set various player-specific options for the final game built by Unity. More info
See in Glossary.
The Web platform supports multithreading, when your document is within a secure context.
The following HTTP response headers must be set by the server.
The recommended way to perform complex asynchronous tasks on the Web platform is to use coroutines. For more information, refer to the coroutines documentation.
The following factors limit the multithreading support:
The Web platform uses WebAssembly, which is a bytecode format for secure and efficient execution of Unity code in web browsers. Web browsers are designed to run the code in a secure and isolated environment which blocks direct access to the native WebAssembly stack. This affects multithreaded garbage collection as the Web garbage collector runs only once at the end of every frame unlike incrementally over multiple frames on other platforms.
Background Workers on the web execute code in parallel independently from each other. On native platforms, the main thread can synchronously send signals to the other threads to pause for garbage collection. This synchronous signaling isn’t supported on the web, which prevents WebAssembly compiled C# code from running in multiple threads.