function pageLoaded(){
var canvas = document.getElementById('testcanvas');//得到画布
var context = canvas.getContext('2d');//得到绘图环境 参数为绘图环境的类型
//检查音频支持
var audiotest = document.createElement('audio');
var mp3Support,oggSupport,wavSupport;
if(audiotest.canPlayType){
/*
MP3格式：字符串audio/mpeg;支持的浏览器：IE9+、Chrome
Vorbis格式：字符串audio/ogg，codecs=”vorbis”;支持的浏览器：Firefox 3.5+、Chrome、Opera 10.5+
WAV格式：字符串audio/wav，codecs=”1”;支持的浏览器：Firefox 3.5+、Opera 10.5+、Chrome
*/
mp3Support = "" != audiotest.canPlayType('audio/mpeg');
oggSupport = "" != audiotest.canPlayType('audio/ogg; codecs = "vorbis"');
wavSupport = "" != audiotest.canPlayType('audio/wav，codecs="1"');
} else{
mp3Support = false;
oggSupport = false;
wavSupport = false;
}
var soundFileExtn = oggSupport?'.ogg':mp3Support?'.mp3':wavSupport?'.wav':undefined;
if(soundFileExtn){
//动态加载audio文件
var audio = new Audio();
//等待音频文件加载完成 然后再播放
audio.addEventListener('canplaythrough',function(){
audio.play();
});
audio.src="/testmusic/8466/8466"+soundFileExtn;
}
}