实现图片预览 属性： error onload readyState result
方法： readAsArrayBuffer() readAsBinaryString() readAsDataURL() readAsText()
事件：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <title>filereader</title> </head> <body> <input type="file" name="file" id="myfile" multiple/> <img src="" id="myimg" width="200px" height="200px" /> <script type="text/javascript"> var fileInput = document.getElementById('myfile'); fileInput.addEventListener("change", function(e){ var fileReader = new FileReader(); fileReader.onload = function(e){ document.getElementById('myimg').setAttribute('src', e.target.result); } fileReader.readAsDataURL(e.target.files[0]); }, false); </script> </body> </html>