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How to convert a raw data excel to a downloadable one?

I receive a raw data of an excel when I send my http request. I am using fileSaver package to save base64 files like pdf (turned into a blob) with it and it works alright. what I receive is as the image below. My question is how can I turn this into saveable blob without data corruption? note that when I save this sting as file in postman it saves fine.
this approach did not work and saves a corrupt excel that cannot be opened:
var blob = new Blob([s2ab(response)], {
type: "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
});
FileSaver.saveAs(blob, action.payload.culture + ".xlsx");

Solved in this way:
before you do anything add arrayBuffer as response-type to your http req header.
firstly convert the binary of arraybuffer to base64:
export function arrayBufferToBase64(buffer: ArrayBufferLike) {
let binary = "";
let bytes = new Uint8Array(buffer);
let len = bytes.byteLength;
for (let i = 0; i < len; i++) {
binary += String.fromCharCode(bytes[i]);
}
return window.btoa(binary);
}
then decode this base64 to a blob:
export const base64toBlob = (b64Data: string, contentType = "", sliceSize = 512): Blob => {
const byteCharacters = atob(b64Data);
const byteArrays = [];
for (let offset = 0; offset < byteCharacters.length; offset += sliceSize) {
const slice = byteCharacters.slice(offset, offset + sliceSize);
const byteNumbers = new Array(slice.length);
for (let i = 0; i < slice.length; i++) {
byteNumbers[i] = slice.charCodeAt(i);
}
const byteArray = new Uint8Array(byteNumbers);
byteArrays.push(byteArray);
}
const blob = new Blob(byteArrays, { type: contentType });
return blob;
};
Now download it:
const blob = base64toBlob(arrayBufferToBase64(response.data));
FileSaver.saveAs(blob, `${orderType}_${formatedDates.from}_${formatedDates.to}.xlsx`);

I want to convert base64 to blob in Objective-c

This is JavaScript code which convert base64 to blob.
but I want to make this kind of code in objective-c.
I can't search in stack overflow.
function base64_to_blob(base64String) {
var byteString = window.atob(base64String);
var array = new Uint8Array(byteString.length);
for (var i = 0; I < byteString.length; I++) {
array[i] = byteString.charCodeAt(i);
}
var blob = new Blob([array], {
type: ‘image / jpeg’,
name: “image.jpg”
});
return blob;
}
Please Help me.

Time use this code my be helpful for you if.
-(NSData *) base64_to_blob(base64String) {
NSData * blobData = [[NSData alloc] initWithBase64EncodedString: base64String options:1];
return blobData;
}

Converting base64 Image to file object in JavaScript

I am trying to create a file object from a base64 image which was cut from another image. I am able to do it but the resulting file size is almost thrice the actual size. Below is the function that I am using:
convertDataURItoFile(dataURI, fileName) {
// convert base64 to raw binary data held in a string
// doesn't handle URLEncoded DataURIs - see SO answer #6850276 for code that does this
var byteString = atob(dataURI.split(',')[1]);
// separate out the mime component
var mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0]
// write the bytes of the string to an ArrayBuffer
var ab = new ArrayBuffer(byteString.length);
var ia = new Uint8Array(ab);
for (var i = 0; i < byteString.length; i++) {
ia[i] = byteString.charCodeAt(i);
}
// write the ArrayBuffer to a blob, and you're done
var blob: any = new Blob([ia], { type: mimeString });
//A Blob() is almost a File() - it's just missing the two properties below which we will add
blob.lastModifiedDate = new Date();
blob.name = fileName;
//Cast to a File() type
return <File>blob;
}
Any idea on why the file size increasing so drastically? How can I compress it? Thanks in advance.

I am trying to create a file object from a base64 image which was cut
from another image. I am able to do it but the resulting file size is
almost thrice the actual size.
Cannot reproduce resulting .size of Blob being thrice the size of the content of input data URI. Do you mean the data URI .length can be thrice the size of Blob .size?
function convertDataURItoFile(dataURI, fileName) {
// convert base64 to raw binary data held in a string
// doesn't handle URLEncoded DataURIs - see SO answer #6850276 for code that does this
var byteString = atob(dataURI.split(',')[1]);
// separate out the mime component
var mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0]
// write the bytes of the string to an ArrayBuffer
var ab = new ArrayBuffer(byteString.length);
var ia = new Uint8Array(ab);
for (var i = 0; i < byteString.length; i++) {
ia[i] = byteString.charCodeAt(i);
}
// write the ArrayBuffer to a blob, and you're done
var blob = new Blob([ia], { type: mimeString });
//A Blob() is almost a File() - it's just missing the two properties below which we will add
blob.lastModifiedDate = new Date();
blob.name = fileName;
//Cast to a File() type
console.log(`input data size: ${datauriLength} Blob.size: ${blob.size}`);
return blob;
}
const [datauri, filename] = ["data:image/png;base64,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", "filename.png"];
const datauriLength = datauri.length;
const reader = new FileReader;
reader.onload = () => {
console.log(`data URI: ${reader.result}`)
document.querySelector("iframe").src = reader.result;
};
reader.readAsDataURL(convertDataURItoFile(datauri, filename));
<iframe></iframe>
If .name and .lastModifiedDate need to be added to Blob, you can substitute using File constructor for Blob, which expects file name parameter to be set at second parameter to File constructor, and optionally expected .lastModidied and or .lastModifiedDate parameters at third parameter to constructor.
function convertDataURItoFile(dataURI, fileName) {
// convert base64 to raw binary data held in a string
// doesn't handle URLEncoded DataURIs - see SO answer #6850276 for code that does this
var byteString = atob(dataURI.split(',')[1]);
// separate out the mime component
var mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0]
// write the bytes of the string to an ArrayBuffer
var ab = new ArrayBuffer(byteString.length);
var ia = new Uint8Array(ab);
for (var i = 0; i < byteString.length; i++) {
ia[i] = byteString.charCodeAt(i);
}
// write the ArrayBuffer to a blob, and you're done
// use `File` constructor here
var blob = new File([ia], fileName, { type: mimeString, lastModifiedDate: new Date() });
//A Blob() is almost a File() - it's just missing the two properties below which we will add
// blob.lastModifiedDate = new Date();
// blob.name = fileName;
//Cast to a File() type
console.log(`input data size: ${datauriLength} Blob.size: ${blob.size}`);
return blob;
}
const [datauri, filename] = ["data:image/png;base64,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", "filename.png"];
const datauriLength = datauri.length;
const reader = new FileReader;
reader.onload = () => {
console.log(`data URI: ${reader.result}`)
document.querySelector("iframe").src = reader.result;
};
reader.readAsDataURL(convertDataURItoFile(datauri, filename));
<iframe></iframe>
You can also utilize fetch() to create and get Blob representation of data URI, see Answer by #Endless at Creating a Blob from a base64 string in JavaScript

Javascript convert blob to string and back

I can convert a blob to string using FileReader, but I want to convert it back:
var reader = new window.FileReader();
reader.readAsDataURL(blob);
reader.onloadend = function() {
base64data = reader.result;
var blobToSend = base64data.substr(base64data.indexOf(',')+1);
rtcMultiConnection.send({"command":{
"recording":blobToSend,
"type":blob.type,
"size":blob.size
}});
}
This is sent with https://github.com/muaz-khan/RTCMultiConnection but the main question is how to reconstruct the blob after being sent. Sadly sending the blob as is didn't work.

source: Creating a Blob from a base64 string in JavaScript
This method correctly converts back base64 data to the original binary data.
For the sake of performance improvements, the data is processed in blocks of the size of sliceSize.
NOTE: source is in TypeScript
public static Base64ToBlob(b64Data, contentType = "", sliceSize = 512): Blob
{
const byteCharacters = atob(b64Data);
const byteArrays = [];
for (let offset = 0; offset < byteCharacters.length; offset += sliceSize)
{
const slice = byteCharacters.slice(offset, offset + sliceSize);
const byteNumbers = new Array(slice.length);
for (let i = 0; i < slice.length; i++)
{
byteNumbers[i] = slice.charCodeAt(i);
}
const byteArray = new Uint8Array(byteNumbers);
byteArrays.push(byteArray);
}
const blob = new Blob(byteArrays, { type: contentType });
return blob;
}

outputting HTML5 canvas as an image, howto?

I have already looked into this tutorial on how to use canvas in HTML5 to create a clipping mask.
http://www.benbarnett.net/2011/06/02/using-html5-canvas-for-image-masks/
The question i have now is it possible to save the canvas as an image (including the mask effect) ?
thanks

Getting PNG output can be done with canvas.toDataURL().
It is also possible to get JPEG output on Chrome/Firefox. Below is a code to convert to JPEG data as HTML5 Blob.
/**
* http://stackoverflow.com/questions/4998908/convert-data-uri-to-file-then-append-to-formdata/5100158
*
*
*/
function dataURItoBlob(dataURI, callback) {
// convert base64 to raw binary data held in a string
// doesn't handle URLEncoded DataURIs
var byteString;
if (dataURI.split(',')[0].indexOf('base64') >= 0) {
byteString = atob(dataURI.split(',')[1]);
} else {
byteString = unescape(dataURI.split(',')[1]);
}
// separate out the mime component
var mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0];
// write the bytes of the string to an ArrayBuffer
var ab = new ArrayBuffer(byteString.length);
var ia = new Uint8Array(ab);
for (var i = 0; i < byteString.length; i++) {
ia[i] = byteString.charCodeAt(i);
}
// write the ArrayBuffer to a blob, and you're done
var BlobBuilder = window.WebKitBlobBuilder || window.MozBlobBuilder;
var bb = new BlobBuilder();
bb.append(ab);
return bb.getBlob(mimeString);
}
function getAsJPEGBlob(canvas) {
if(canvas.mozGetAsFile) {
return canvas.mozGetAsFile("foo.jpg", "image/jpeg");
} else {
var data = canvas.toDataURL('image/jpeg', 0.7);
var blob = dataURItoBlob(data);
return blob;
}
}

canvas.toDataURL();
is a function to get you a Data URL which you can put into an image tag. From there you can save it.
If you're looking to automatically save it to the harddrive, that isn't possible in standard JavaScript