js操作文件 HTML5版，有需要的朋友可以参考下。
<!DOCTYPE html>
<html>
<head>
<title>JSFileReader</title>
<meta charset="utf-8" >
</head>
<body>
<input accept="image/*" type="file" name="fileImg" id="fileImg" />
<input type="button" onclick="readAsDataURL()" value="readAsDataURL">
<input type="button" onclick="readAsBinaryString()" value="readAsBinaryString"><br><br>
<input accept="text/*" type="file" name="fileTxt" id="fileTxt" />
<input type="button" onclick="readAsArrayBuffer()" value="readAsArrayBuffer">
<input type="button" onclick="readAsText()" value="readAsText"><br><br>
<input type="file" name="file" id="file" multiple />
<input type="button" onclick="readAttr()" value="readAttr"><br><br>
<input type="button" onclick="saveTXT()" value="saveTXT"><br><br>
<div id="result"></div>
<script type="text/javascript">
var imgs = document.getElementById('fileImg');
var txts = document.getElementById('fileTxt');
var files = document.getElementById('file');
var result = document.getElementById('result');
if (typeof FileReader == 'undefined') {
img.disabled = true;
txt.disabled = true;
file.disabled = true;
alert('您的浏览器太老了');
}else {
var reader = new FileReader();
}
function readAsDataURL(){
img = imgs.files[0];
if (typeof img == 'undefined') {alert('选择对应文件');return;}
if (!/image/w+/.test(img.type)) {alert('not image');return;}
reader.readAsDataURL(img);
reader.onload = function (e){
result.innerHTML += "<img src='"+this.result+"'' />";
}
}
function readAsBinaryString(){
img = imgs.files[0];
if (typeof img == 'undefined') {alert('选择对应文件');return;}
if (!/image/w+/.test(img.type)) {alert('not img');return;}
reader.readAsBinaryString(img);
reader.onload = function (e){
result.innerHTML += this.result;
}
}
function readAsArrayBuffer(){
txt = txts.files[0];
if (typeof txt == 'undefined') {alert('选择对应文件');return;}
if (!/text/w+/.test(txt.type)) {alert('not txt');return;}
reader.readAsArrayBuffer(txt);
reader.onload = function (e){
result.innerHTML += this.result.byteLength+'<br>'+ab2str(this.result);
}
}
// ArrayBuffer转为字符串，参数为ArrayBuffer对象
function ab2str(buf) {
/*Int8Array：8位有符号整数，长度1个字节。
Uint8Array：8位无符号整数，长度1个字节。
Int16Array：16位有符号整数，长度2个字节。
Uint16Array：16位无符号整数，长度2个字节。
Int32Array：32位有符号整数，长度4个字节。
Uint32Array：32位无符号整数，长度4个字节。
Float32Array：32位浮点数，长度4个字节。
Float64Array：64位浮点数，长度8个字节。*/
return String.fromCharCode.apply(null, new Uint8Array(buf));
}
// 字符串转为ArrayBuffer对象，参数为字符串
function str2ab(str) {
var buf = new ArrayBuffer(str.length*2); // 每个字符占用2个字节
var bufView = new Uint8Array(buf);
for (var i=0, strLen=str.length; i<strLen; i++) {
bufView[i] = str.charCodeAt(i);
}
return buf;
}
function readAsText(){
txt = txts.files[0];
if (typeof txt == 'undefined') {alert('选择对应文件');return;}
if (!/text/w+/.test(txt.type)) {alert('not txt');return;}
reader.readAsText(txt,'utf-8');
reader.onloadstart = function (e){
alert('开始读取...');
}
reader.onprogress = function (e){
alert('读取中...');
//reader.abort();
}
reader.onload = function (e){//载入成功
result.innerHTML += this.result;
}
reader.onloadend = function (e){
alert('载入完成即触发 不管成功与否');
}
reader.onerror = function (e){
alert('读取出错时触发');
}
reader.onabort = function (e){
alert('读取中断时触发');
}
}
function readAttr(){
img = imgs.files[0];
txt = txts.files[0];
if (typeof img == 'undefined' || typeof txt == 'undefined') {alert('选择对应文件');return;}
for(i in img)
result.innerHTML += i+"====>"+img[i]+"<br>";
result.innerHTML += "<br>";
for(i in txt)
result.innerHTML += i+"====>"+txt[i]+"<br>";
for (var i = 0; i < files.files.length; i++) {
var multipleFile = file.files[i];
if (typeof multipleFile == 'undefined') {alert('选择对应文件');return;}
for(j in multipleFile)
result.innerHTML += j+"====>"+multipleFile[j]+"<br>";
result.innerHTML += "<br>";
}
}
function saveTXT(){
if (!result.innerHTML) {alert('没有数据 无需导出');return;}
var URL = URL || webkitURL || window;
var bb = new Blob([result.innerHTML],{ "type" : "text/plain;charset=utf-8" }); // the blob
saveAs(bb, 'saveTXT.txt');
}
function saveAs(blob, filename){
var type = blob.type;
var force_saveable_type = 'application/octet-stream';
if (type && type != force_saveable_type) { // 强制下载，而非在浏览器中打开
var slice = blob.slice || blob.webkitSlice || blob.mozSlice;
blob = slice.call(blob, 0, blob.size, force_saveable_type);
}
var url = URL.createObjectURL(blob);
var save_link = document.createElementNS('http://www.w3.org/1999/xhtml', 'a');//方法可创建带有指定命名空间的元素节点。
save_link.href = url;
save_link.download = filename;
var event = document.createEvent('MouseEvents');
event.initMouseEvent('click', true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
save_link.dispatchEvent(event);
URL.revokeObjectURL(url);
}
</script>
</body>
</html>