JS+HTML5 FileReader对象用法示例

<input name="file" id="uploadFile" />

var file = document.getElementById("uploadFile");var bufferSize = 1024;var pos = 0;var onload = function(e) {   console.log("Read", e.target.result);   var img = document.createElement("img");   img.src = e.target.result;   img.width = 300;   img.height = 300;   document.body.appendChild(img);};var onerror = function() {}var onprogress = function(e) {}file.onchange = function() {   if (file.files) file = file.files[0];   while (pos < file.size) {    var reader = new FileReader();    reader.onload = onload;    reader.onerror = onerror;    /*reader.readAsText(file.slice(pos, bufferSize));    pos += bufferSize; */    reader.readAsDataURL(file);    pos = file.size + 1;   }}