three.js/examples/js/WebGL.js

( function () {

	var WEBGL = {
		isWebGLAvailable: function () {

			try {

				var canvas = document.createElement( 'canvas' );
				return !! ( window.WebGLRenderingContext && ( canvas.getContext( 'webgl' ) || canvas.getContext( 'experimental-webgl' ) ) );

			} catch ( e ) {

				return false;

			}

		},
		isWebGL2Available: function () {

			try {

				var canvas = document.createElement( 'canvas' );
				return !! ( window.WebGL2RenderingContext && canvas.getContext( 'webgl2' ) );

			} catch ( e ) {

				return false;

			}

		},
		getWebGLErrorMessage: function () {

			return this.getErrorMessage( 1 );

		},
		getWebGL2ErrorMessage: function () {

			return this.getErrorMessage( 2 );

		},
		getErrorMessage: function ( version ) {

			var names = {
				1: 'WebGL',
				2: 'WebGL 2'
			};
			var contexts = {
				1: window.WebGLRenderingContext,
				2: window.WebGL2RenderingContext
			};
			var message = 'Your $0 does not seem to support <a href="http://khronos.org/webgl/wiki/Getting_a_WebGL_Implementation" style="color:#000">$1</a>';
			var element = document.createElement( 'div' );
			element.id = 'webglmessage';
			element.style.fontFamily = 'monospace';
			element.style.fontSize = '13px';
			element.style.fontWeight = 'normal';
			element.style.textAlign = 'center';
			element.style.background = '#fff';
			element.style.color = '#000';
			element.style.padding = '1.5em';
			element.style.width = '400px';
			element.style.margin = '5em auto 0';

			if ( contexts[ version ] ) {

				message = message.replace( '$0', 'graphics card' );

			} else {

				message = message.replace( '$0', 'browser' );

			}

			message = message.replace( '$1', names[ version ] );
			element.innerHTML = message;
			return element;

		}
	};

	THREE.WEBGL = WEBGL;

} )();