Develop Reference

Upload file to AWS S3 using REST API Javascript

I am trying to retrieve a file from the user's file system and upload it to AWS S3. However, I have had no success thus far doing so. To be more specific, I have been working with trying to upload images. So far the images won't render properly whenever I upload them. I am really only familiar with uploading images as Blobs, but since SHA256 function can't read a Blob I'm unsure what to do. Below is my code:
var grabFile = new XMLHttpRequest();
grabFile.open("GET", 'https://s3.amazonaws.com/'+bucketName+'/asd.jpeg', true);
grabFile.responseType = "arraybuffer";
grabFile.onload = function( e ) {
var grabbedFile = this.response;
var arrayBufferView = new Uint8Array( this.response );
var blob = new Blob( [ arrayBufferView ], { type: "image/jpeg" } );
var base64data = '';
var reader = new FileReader();
reader.readAsDataURL(blob);
reader.onloadend = function() {
//var readData = reader.result;
var readData = blob;
//readData = readData.split(',').pop();
console.log(readData);
console.log(readData.toString());
var shaString = CryptoJS.SHA256(readData.toString()).toString();
var request = new XMLHttpRequest();
var signingKey = getSigningKey(dateStamp, secretKey, regionName, serviceName);
var headersList = "content-type;host;x-amz-acl;x-amz-content-sha256;x-amz-date";
var time = new Date();
time = time.toISOString();
time = time.replace(/:/g, '').replace(/-/g,'');
time = time.substring(0,time.indexOf('.'))+"Z";
var canonString = "PUT\n"+
"/asd5.jpeg\n"+
"\n"+
//"content-encoding:base64\n"+
"content-type:image/jpeg\n"+
"host:"+bucketName+".s3.amazonaws.com\n"+
'x-amz-acl:public-read\n'+
'x-amz-content-sha256:'+shaString+"\n"+
'x-amz-date:'+time+'\n'+
'\n'+
headersList+'\n'+
shaString;
var stringToSign = "AWS4-HMAC-SHA256\n"+
time+"\n"+
dateStamp+"/us-east-1/s3/aws4_request\n"+
CryptoJS.SHA256(canonString);
var authString = CryptoJS.HmacSHA256(stringToSign, signingKey).toString();
var auth = "AWS4-HMAC-SHA256 "+
"Credential="+accessKey+"/"+dateStamp+"/"+regionName+"/"+serviceName+"/aws4_request, "+
"SignedHeaders="+headersList+", "+
"Signature="+authString;
request.open("PUT", "https://"+bucketName+".s3.amazonaws.com/asd5.jpeg", true);
request.setRequestHeader("Authorization", auth);
//request.setRequestHeader("content-encoding", "base64");
request.setRequestHeader("content-type", "image/jpeg");
request.setRequestHeader('x-amz-acl', 'public-read');
request.setRequestHeader("x-amz-content-sha256", shaString);
request.setRequestHeader("x-amz-date", time);
request.send(readData.toString());
console.log(request);
How do I go about doing this? The code above just uploads something that's just a few Bytes because blob.toString() comes out as [Object Blob] and that's what gets uploaded. If I don't toString() it, I get an error from my SHA256 function.
As you can see, I tried reading it as Base64 before uploading it, but that did not resolve my problem either. This problem has been bugging me for close to a week now and I would love to get this solved. I've tried changing content-type, changed the body of what I'm uploading, etc. but nothing has worked.
EDIT: Forgot to mention (even though the title should imply it) but I cannot use the SDK for this. I was using it at one point, and with it I was able to upload images as Blobs. So I know this is possible, it's just that I don't know what crafty thing the SDK is doing to upload it.
EDIT2: I found the solution just in case someone stumbles across this in the future. Try setting replace every place I have shaString with 'UNSIGNED PAYLOAD' and send the blob and it will work! Here's where I found it: https://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-header-based-auth.html

Javascript formdata: encrypt files before appending

I need to modify existing frontend (angular) code that involves uploading files to a server. Now the files need to be encrypted before being uploaded.
The current approach uses FormData to append a number of files and send them in a single request as shown below:
function uploadFiles(wrappers){
var data = new FormData();
// Add each file
for(var i = 0; i < wrappers.length; i++){
var wrapper = wrappers[i];
var file = wrapper.file;
data.append('file_' + i, file);
}
$http.post(uri, data, requestCfg).then(
/*...*
I have been using Forge in other projects, but never in this sort of context and don't really see how to encrypt files on the fly and still append them as FormData contents.
Forge provides an easy API:
var key = forge.random.getBytesSync(16);
var iv = forge.random.getBytesSync(8);
// encrypt some bytes
var cipher = forge.rc2.createEncryptionCipher(key);
cipher.start(iv);
cipher.update(forge.util.createBuffer(someBytes));
cipher.finish();
var encrypted = cipher.output;
The backend recieves files using Formidable and all the file hanlding is already wired. I would thus like to stick to using the existing front-end logic but simply insert the encryption logic. In that, it's not the entire formdata that must be encrypted... I haven't found a good lead yet to approach this.
Suggestions are very welcome!

Ok, found a solution and added the decrypt code as well. This adds a layer of async code.
function appendFile(aFile, idx){
// Encrypt if a key was provided for this protocol test
if(!key){
data.append('dicomfile_' + idx, file);
appendedCount++;
onFileAppended();
}
else{
var reader = new FileReader();
reader.onload = function(){
// 1. Read bytes
var arrayBuffer = reader.result;
var bytes = new Uint8Array(arrayBuffer); // byte array aka uint8
// 2. Encrypt
var cipher = forge.cipher.createCipher('AES-CBC', key);
cipher.start({iv: iv});
cipher.update(forge.util.createBuffer(bytes));
cipher.finish();
// 3. To blob (file extends blob)
var encryptedByteCharacters = cipher.output.getBytes(); // encryptedByteCharacters is similar to an ATOB(b64) output
// var asB64 = forge.util.encode64(encryptedBytes);
// var encryptedByteCharacters = atob(asB64);
// Convert to Blob object
var blob = byteCharsToBlob(encryptedByteCharacters, "application/octet-stream", 512);
// 4. Append blob
data.append('dicomfile_' + idx, blob, file.name);
// Decrypt for the sake of testing
if(true){
var fileReader = new FileReader();
fileReader.onload = function() {
arrayBuffer = this.result;
var bytez = new Uint8Array(arrayBuffer);
var decipher = forge.cipher.createDecipher('AES-CBC', key);
decipher.start({iv: iv});
decipher.update(forge.util.createBuffer(bytez));
decipher.finish();
var decryptedByteCharacters = decipher.output.getBytes();
var truz = bytes === decryptedByteCharacters;
var blob = byteCharsToBlob(decryptedByteCharacters, "application/octet-stream", 512);
data.append('decrypted_' + idx, blob, file.name + '.decrypted');
appendedCount++;
onFileAppended();
};
fileReader.readAsArrayBuffer(blob);
}
else{
// z. Resume processing
appendedCount++;
onFileAppended();
}
}
// Read file
reader.readAsArrayBuffer(aFile);
}
}
function onFileAppended(){
// Only proceed when all files were appended and optionally encrypted (async)
if(appendedCount !== wrappers.length) return;
/* resume processing, upload or do whathever */

Generate a blob with grunt which will be available to JS in var

I need to embed a Flash .swf on the page and am unable use the normal way of setting the src or data attribute to the swf url - don't ask :s. So, I'm doing an ajax request for the swf, converting to a blob and then generating a blob url which I set as the swf src. Then I realised that as I'm building with Grunt, there may be a way to just write the swf file into the code as a blob in a var, and avoid the ajax request completely. Here's the code with the ajax request:
function createFlashMovie(blobUrl){
var obj = document.createElement("object");
obj.setAttribute("width", "800");
obj.setAttribute("height", "600");
obj.setAttribute("type", "application/x-shockwave-flash");
obj.setAttribute("data", blobUrl);
document.body.appendChild(obj);
}
function onAjaxLoad(oResponse){
blobUrl = window.URL.createObjectURL(oResponse);
createFlashMovie(blobUrl);
};
//do the xhr request for a.swf
var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function(){
if (this.readyState == 4 && this.status == 200){
onAjaxLoad(this.response);
}
}
xhr.open('GET', '//theserver.com/a.swf');
xhr.responseType = 'blob';
xhr.send();
...but I'm sure it must be possible to have something like this which is replaced by grunt to have the blob already available when it runs, and go straight to creating the blob url without the xhr request:
var theBlob = new Blob(["GRUNT_WRITES_THIS_IN_FROM_FILE"], {type: "application/x-shockwave-flash"});

Well, grunt is at its core just a Node program, so you can use any node command in your Gruntfile or tasks definitions. And it seems that Node's http.request would be perfect for your needs.
So:
add a custom task in your Gruntfile (http://gruntjs.com/creating-tasks#custom-tasks)
that uses http.request to download your swf (https://docs.nodejitsu.com/articles/HTTP/clients/how-to-create-a-HTTP-request)
update your code to use the local swf

I found a solution. Convert your swf file to be a base64-encoded string. At the moment I'm doing this separately and then pasting it into the source JS, but it can be automated at build time with grunt. Then in the page script create a var to store it as a dataURI:
var swfAsDataUri = "data:application/x-shockwave-flash;base64,BIG_LONG_CHUNK_OF_DATA_THAT_IS_YOUR_ENCODED_SWF_FILE__GRUNT_CAN_WRITE_THIS_IN_AT_BUILD_TIME";
Create a blob from the data url, and then create an object url from the blob:
//function taken from http://stackoverflow.com/questions/27159179/how-to-convert-blob-to-file-in-javascript
dataURLToBlob = function(dataURL) {
var BASE64_MARKER = ';base64,';
var parts = dataURL.split(BASE64_MARKER);
var contentType = parts[0].split(':')[1];
var raw = window.atob(parts[1]);
var rawLength = raw.length;
var uInt8Array = new Uint8Array(rawLength);
for (var i = 0; i < rawLength; ++i) {
uInt8Array[i] = raw.charCodeAt(i);
}
return new Blob([uInt8Array], {type: contentType});
};
var blobUrl = window.URL.createObjectURL( dataURLToBlob(swfAsDataUri) );
You can then use the object url as the src data for the flash movie's object tag when it's embedded:
function createFlashMovie(blobUrl){
var obj = document.createElement("object");
obj.setAttribute("width", "800");
obj.setAttribute("height", "600");
obj.setAttribute("type", "application/x-shockwave-flash");
obj.setAttribute("data", blobUrl); //use the object url here
document.body.appendChild(obj);
}
...and there you have it, no additional http request for the swf file.

Excel to JSON javascript code?

I want to convert excel sheet data to json. It has to be dynamic, so there is an upload button where user uploads the excel sheet and the data is then converted into json. Could you please provide me the javascript code? I tried SheetJS but couldn't figure out. I would prefer something straight forward :)
I really appreciate your help!

NOTE: Not 100% Cross Browser
Check browser compatibility # http://caniuse.com/#search=FileReader
as you will see people have had issues with the not so common browsers, But this could come down to the version of the browser.. I always recommend using something like caniuse to see what generation of browser is supported... This is only a working answer for the user, not a final copy and paste code for people to just use..
The Fiddle: http://jsfiddle.net/d2atnbrt/3/
THE HTML CODE:
<input type="file" id="my_file_input" />
<div id='my_file_output'></div>
THE JS CODE:
var oFileIn;
$(function() {
oFileIn = document.getElementById('my_file_input');
if(oFileIn.addEventListener) {
oFileIn.addEventListener('change', filePicked, false);
}
});
function filePicked(oEvent) {
// Get The File From The Input
var oFile = oEvent.target.files[0];
var sFilename = oFile.name;
// Create A File Reader HTML5
var reader = new FileReader();
// Ready The Event For When A File Gets Selected
reader.onload = function(e) {
var data = e.target.result;
var cfb = XLS.CFB.read(data, {type: 'binary'});
var wb = XLS.parse_xlscfb(cfb);
// Loop Over Each Sheet
wb.SheetNames.forEach(function(sheetName) {
// Obtain The Current Row As CSV
var sCSV = XLS.utils.make_csv(wb.Sheets[sheetName]);
var oJS = XLS.utils.sheet_to_row_object_array(wb.Sheets[sheetName]);
$("#my_file_output").html(sCSV);
console.log(oJS)
});
};
// Tell JS To Start Reading The File.. You could delay this if desired
reader.readAsBinaryString(oFile);
}
This also requires https://cdnjs.cloudflare.com/ajax/libs/xls/0.7.4-a/xls.js to convert to a readable format, i've also used jquery only for changing the div contents and for the dom ready event.. so jquery is not needed
This is as basic as i could get it,
EDIT - Generating A Table
The Fiddle: http://jsfiddle.net/d2atnbrt/5/
This second fiddle shows an example of generating your own table, the key here is using sheet_to_json to get the data in the correct format for JS use..
One or two comments in the second fiddle might be incorrect as modified version of the first fiddle.. the CSV comment is at least
Test XLS File: http://www.whitehouse.gov/sites/default/files/omb/budget/fy2014/assets/receipts.xls
This does not cover XLSX files thought, it should be fairly easy to adjust for them using their examples.

js-xlsx library makes it easy to convert Excel/CSV files into JSON objects.
Download the xlsx.full.min.js file from here.
Write below code on your HTML page
Edit the referenced js file link (xlsx.full.min.js) and link of Excel file
<!doctype html>
<html>
<head>
<title>Excel to JSON Demo</title>
<script src="xlsx.full.min.js"></script>
</head>
<body>
<script>
/* set up XMLHttpRequest */
var url = "http://myclassbook.org/wp-content/uploads/2017/12/Test.xlsx";
var oReq = new XMLHttpRequest();
oReq.open("GET", url, true);
oReq.responseType = "arraybuffer";
oReq.onload = function(e) {
var arraybuffer = oReq.response;
/* convert data to binary string */
var data = new Uint8Array(arraybuffer);
var arr = new Array();
for (var i = 0; i != data.length; ++i) arr[i] = String.fromCharCode(data[i]);
var bstr = arr.join("");
/* Call XLSX */
var workbook = XLSX.read(bstr, {
type: "binary"
});
/* DO SOMETHING WITH workbook HERE */
var first_sheet_name = workbook.SheetNames[0];
/* Get worksheet */
var worksheet = workbook.Sheets[first_sheet_name];
console.log(XLSX.utils.sheet_to_json(worksheet, {
raw: true
}));
}
oReq.send();
</script>
</body>
</html>
Input:
Output:

The answers are working fine with xls format but, in my case, it didn't work for xlsx format. Thus I added some code here. it works both xls and xlsx format.
I took the sample from the official sample link.
Hope it may help !
function fileReader(oEvent) {
var oFile = oEvent.target.files[0];
var sFilename = oFile.name;
var reader = new FileReader();
var result = {};
reader.onload = function (e) {
var data = e.target.result;
data = new Uint8Array(data);
var workbook = XLSX.read(data, {type: 'array'});
console.log(workbook);
var result = {};
workbook.SheetNames.forEach(function (sheetName) {
var roa = XLSX.utils.sheet_to_json(workbook.Sheets[sheetName], {header: 1});
if (roa.length) result[sheetName] = roa;
});
// see the result, caution: it works after reader event is done.
console.log(result);
};
reader.readAsArrayBuffer(oFile);
}
// Add your id of "File Input"
$('#fileUpload').change(function(ev) {
// Do something
fileReader(ev);
}

#Kwang-Chun Kang Thanks Kang a lot! I found the solution is working and very helpful, it really save my day.
For me I am trying to create a React.js component that convert *.xlsx to json object when user upload the excel file to a html input tag.
First I need to install XLSX package with:
npm install xlsx --save
Then in my component code, import with:
import XLSX from 'xlsx'
The component UI should look like this:
<input
accept=".xlsx"
type="file"
onChange={this.fileReader}
/>
It calls a function fileReader(), which is exactly same as the solution provided.
To learn more about fileReader API, I found this blog to be helpful:
https://blog.teamtreehouse.com/reading-files-using-the-html5-filereader-api

This is my expansion on https://stackoverflow.com/a/52237535/5079799
While it was working/great example, I'm not using an input form, but fetching from a URL and I have other things to do after fething workbook so I needed to wrap the onload into a promise.
See --> adjust onload function to be used with async/await
Here is what I ended up w/
async function Outside_Test(){
var reso = await Get_JSON()
console.log('reso_out')
console.log(reso)
}
async function Get_JSON() {
var url = "http://MyworkbookURL"
var workbook = await Get_XLSX_As_Workbook_From_URL(url)
/* DO SOMETHING WITH workbook HERE */
var first_sheet_name = workbook.SheetNames[0];
/* Get worksheet */
var worksheet = workbook.Sheets[first_sheet_name];
var reso = (XLSX.utils.sheet_to_json(worksheet, {
raw: true
}));
return reso
}
async function Get_XLSX_As_Workbook_From_URL(url) {
const arrayBuffer = await new Promise((resolve, reject) => {
var oReq = new XMLHttpRequest();
oReq.open("GET", url, true);
oReq.responseType = "arraybuffer";
oReq.onload = () => resolve(oReq.response);
oReq.onerror = reject;
oReq.send();
});
var data = new Uint8Array(arrayBuffer);
var arr = new Array();
for (var i = 0; i != data.length; ++i) arr[i] = String.fromCharCode(data[i]);
var bstr = arr.join("");
var workbook = XLSX.read(bstr, {
type: "binary"
});
return workbook
}

XMLHttpRequest POST formData to a new tab [duplicate]

This question already has an answer here:
How to pass formData to postData in loadOneTab?
(1 answer)
Closed 8 years ago.
Since, loadOneTab() is not available for formData,
How can formData be posted to a new tab?
How can the above new tab foreground/background status be set?
Just a smaple example from Using FormData Objects:
var formData = new FormData();
formData.append("username", "Groucho");
formData.append("accountnum", 123456); // number 123456 is immediately converted to string "123456"
// HTML file input user's choice...
formData.append("userfile", fileInputElement.files[0]);
// JavaScript file-like object...
var content = '<a id="a"><b id="b">hey!</b></a>'; // the body of the new file...
var blob = new Blob([content], { type: "text/xml"});
formData.append("webmasterfile", blob);
var request = new XMLHttpRequest();
request.open("POST", "http://foo.com/submitform.php");
request.send(formData);
Clarification:
Normal HTML form with a target="_blank" will POST the form data to a new tab.
Similarly, as mentioned, loadOneTab() can also POST data to a new tab.
Is it possible to do so with XMLHttpRequest?

XHR has absolutely nothing to do with tabs. If you really want to XHR it, then you should take the returned source and update document of the target tab with it.
Otherwise I would just use loadOneTab:
I would think something like this where things are turned into nsIFile:
Import encodeFormData function form here: https://stackoverflow.com/a/25020668/3791822
// HTML file input user's choice...
var userfileNSIFILE = new FileUtils.File(fileInputElement.files[0].path);
// JavaScript file-like object...
var content = '<a id="a"><b id="b">hey!</b></a>'; // the body of the new file...
var blob = new Blob([content], { type: "text/xml"});
//some code here to write blob to temp folder to make nsifile or do some stream stuff to get an nisfileoutputstream?
var blobNSIFILE = ....;
let postData = encodeFormData({
"webmasterfile": blobNSIFILE,
"userfile": userfileNSIFILE,
"username": "Groucho",
"accountnum": 123456
}, "iso8859-1");
gBrowser.loadOneTab("http://foo.com/submitform.php", {
inBackground: false,
postData: postData
});

This is what I mean by loading responseText of xhr into a tab, can copy paste to scratchpad.
var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function() {
switch (xhr.readyState) {
case 4:
prompt('done', xhr.responseText);
gBrowser.loadOneTab('data:text/html, ' + encodeURIComponent(xhr.responseText), {
inBackground: false
});
break;
default:
}
};
xhr.open("GET", "https://www.bing.com/");
xhr.send();