modernizr.js

        if(Modernizr.canvas){
            alert(123);
        }else{
            alert(321);
        }    

    function supert_canvas(){
        if(Modernizr.canvas){
            alert("是");
        }else{
            alert("否");
        }
    
    }

function supert_canvas(id){ 
　　return !! document.getElementById(id).getContext("2d"); 
}

 if(Modernizr.canvastext){
      alert(123);
 }else{
      alert(321);
}    

function supert_canvas1_fillText(){
   var canvas1 = document.getElementById("canvas1");
   var context = canvas1.getContext("2d");
    return typeof context.fillText == ‘function‘;
}

function supert_video (id){
    return !! document.getElementById(id).canPlayType;
}

 if(Modernizr.video){
      alert("支持");
 }else{
      alert("不支持");
}   

function support_webm_video(){
  if(!support_video()){ return false}
  var v = document.createElement("video");
  return v.canPlayType(‘video/webm; codecs="vp8,varbis"‘);  

}

function supports_webm_video(){
    if(Modernizr.video){
        // 可以播放视频了,但是播放哪一种格式呢?
        if(Modernizr.video.oog){
            // 尝试在 Ogg 容器中使用 Ogg Theora + Vorbis 
        }else if (){
            // 尝试在 MP4 容器中使用 h.264 视频 + AAC  音频
        }
    
    }
}

function support_local_storage(){

    return (‘localStorage‘ in window ) && window[‘localStorage‘] != null;
}   

    if(Modernizr.localstorage){
        alert("ok");
    }else{
        alert("no ok");
    }

function support_web_workers(){
    return !! window.Worker;

}

        if(Modernizr.webworkers){
        }else{
        }

function support_offline(){
    return !! window.applicationcache;
}

        if(Modernizr.applicationcache){
        }else{
        }

function support_geolocation(){
    return !! window.geolocation;
}

        if(Modernizr.geolocation){
        }else{
        }

        if(Modernizr.inputtypes.data){
        }else{
        }

        if(Modernizr.input.placeholder){
        }else{
        }

        if(Modernizr.input.autofocus){
        }else{
        }

function support_input_autofocus(){
    return  ‘autofocus‘ in document.createElement(‘input‘);
}

function support_input_autofocus(){
    return  ‘autofocus‘ in document.createElement(‘input‘);
}