php中通过Ajax如何实现异步文件上传的代码实例

ile = null;
}
dp.prototype = {
init:function(args){
var dropwrap = args.dropwrap;
var _this = this;
dropwrap.addeventlistener("dragenter", this._dragenter, false);
dropwrap.addeventlistener("dragover", this._dragover, false);
dropwrap.addeventlistener(''drop'', function(e){_this.readfile.call(_this,e)} , false);
log(''window drop bind--ok'');
},
_dragenter:function(e){e.stoppropagation();e.preventdefault();},
_dragover:function(e){e.stoppropagation();e.preventdefault();},
readfile:function(e){
e.stoppropagation();
e.preventdefault();
var dt = e.datatransfer;
var files = dt.files;
for(var i = 0; i< files.length;i++){
var html = html.slice();
html = this.writeheader(files[i], html);
this.read(files[i], html);
}
},
read:function(file, h){
var type = file.type;
var reader = new filereader();
reader.onprogress = function(e){
if (e.lengthcomputable){
log(''progress: '' + math.ceil(100*e.loaded/file.size) +''%'')
}
};
reader.onloadstart = function(e){
log(''onloadstart: ok'');
};
reader.onloadend = function(e){
var _result = e.target.result;
//console[''log''](e.target);
log(''data uri--ok'');
var d = document.createelement(''div'');
h = h.replace(''$filebase64