Three.js利用Detector.js插件如何实现兼容性检测详解

<script src="examples/js/Detector.js"></script> 

if ( ! Detector.webgl ) Detector.addGetWebGLMessage(); 

/ 
  @author alteredq / http://alteredqualia./ 
  @author mr.doob / http://mrdoob./ 
 / 
 
var Detector = { 
 
 canvas: !! window.CanvasRenderingContext2D, 
 webgl: ( function () { 
 
 try { 
 
  var canvas = document.createElement( 'canvas' ); return !! ( window.WebGLRenderingContext && ( canvas.getContext( 'webgl' ) || canvas.getContext( 'experimental-webgl' ) ) ); 
 
 } catch ( e ) { 
 
  return false; 
 
 } 
 
 } )(), 
 workers: !! window.Worker, 
 fileapi: window.File && window.FileReader && window.FileList && window.Blob, 
 
 getWebGLErrorMessage: function () { 
 
 var element = document.createElement( 'div' ); 
 element.id = 'webgl-error-message'; 
 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 ( ! this.webgl ) { 
 
  element.innerHTML = window.WebGLRenderingContext ? [ 
  'Your graphics card does not seem to support <a href="http://khronos./webgl/wiki/Getting_a_WebGL_Implementation" rel="external nofollow" rel="external nofollow" style="color:#000">WebGL</a>.<br />', 
  'Find out how to get it <a href="http://get.webgl./" rel="external nofollow" rel="external nofollow" style="color:#000">here</a>.' 
  ].join( '\n' ) : [ 
  'Your browser does not seem to support <a href="http://khronos./webgl/wiki/Getting_a_WebGL_Implementation" rel="external nofollow" rel="external nofollow" style="color:#000">WebGL</a>.<br/>', 
  'Find out how to get it <a href="http://get.webgl./" rel="external nofollow" rel="external nofollow" style="color:#000">here</a>.' 
  ].join( '\n' ); 
 
 } 
 
 return element; 
 
 }, 
 
 addGetWebGLMessage: function ( parameters ) { 
 
 var parent, id, element; 
 
 parameters = parameters || {}; 
 
 parent = parameters.parent !== undefined ? parameters.parent : document.body; 
 id = parameters.id !== undefined ? parameters.id : 'oldie'; 
 
 element = Detector.getWebGLErrorMessage(); 
 element.id = id; 
 
 parent.appendChild( element ); 
 
 } 
 
}; 
 
// browserify support 
if ( typeof module === 'object' ) { 
 
 module.exports = Detector; 
 
}