Detect WebGL

{{DefaultAPISidebar("WebGL")}} {{PreviousNext("Web/API/WebGL_API/By_example","Web/API/WebGL_API/By_example/Clearing_with_colors")}} 

This example demonstrates how to detect a {{Glossary("WebGL")}}  rendering context and reports the result to the user.

Feature-detecting WebGL

{{EmbedLiveSample("Feature-detecting_WebGL",660,150)}} 

In this first example we are going to check whether the browser supports {{Glossary("WebGL")}} . To that end we will try to obtain the {{domxref("WebGLRenderingContext","WebGL rendering context","",1)}}  from a {{domxref("HTMLCanvasElement","canvas")}}  element. The {{domxref("WebGLRenderingContext","WebGL rendering context", "", 1)}}  is an interface, through which you can set and query the state of the graphics machine, send data to the WebGL, and execute draw commands.

Saving the state of the graphics machine within a single context interface is not unique to {{Glossary("WebGL")}} . This is also done in other graphics {{Glossary("API")}} , such as the {{domxref("CanvasRenderingContext2D","canvas 2D rendering context", "", 1)}} . However, the properties and variables you can tweak are different for each {{Glossary("API")}} .

<p>[ Here would go the result of WebGL feature detection ]</p>
<button>Press here to detect WebGLRenderingContext</button>

body {
  text-align: center;
}
button {
  display: block;
  font-size: inherit;
  margin: auto;
  padding: 0.6em;
}

const paragraph = document.querySelector("p");
const button = document.querySelector("button");

// Adding click event handler to button.
button.addEventListener("click", detectWebGLContext);
function detectWebGLContext() {
  // Create canvas element. The canvas is not added to the
  // document itself, so it is never displayed in the
  // browser window.
  const canvas = document.createElement("canvas");

  // Get WebGLRenderingContext from canvas element.
  const gl = canvas.getContext("webgl");

  // Report the result.
  paragraph.textContent =
    gl instanceof WebGLRenderingContext
      ? "Congratulations! Your browser supports WebGL."
      : "Failed. Your browser or device may not support WebGL.";
}

The source code of this example is also available on GitHub.

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