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.com/  * @author mr.doob / http://mrdoob.com/  */  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.org/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.org/" rel="external nofollow" rel="external nofollow" style="color:#000">here</a>.'   ].join( '/n' ) : [   'Your browser does not seem to support <a href="http://khronos.org/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.org/" 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;  }