Changing format of the file - javascript

Can I change the format of the file by using Native File System API? For example, when I read the every .pdf files of the one directory and changed them to the .jpeg files?

You can use a library like PDF.js to run the conversion as outlined in this gist. For the actual folder iteration, try this:
const dirHandle = await window.showDirectoryPicker();
for await (const entry of dirHandle.values()) {
if (entry.kind === 'file' && entry.name.endsWith('.pdf')) {
const file = await entry.getFile();
// Convert to image as outlined in gist.
}
}

Related

Attempting to download a .xlsx file and upload to Azure Blob Storage using Playwright with Javascript produces malformed .xlsx file with a bad header

I am trying to download an excel file and then upload it to Azure Blob Storage for use in Azure Data Factory. I have a playwright javascript that worked when the file was a .csv but when I try the same code with an excel file, it will not open in Excel. It says,
"We found a problem with some content in 'order_copy.xlsx'. Do you want us to try to recover as much as we can?:
After clicking yes, it says,
"Excel cannot open the file 'order_copy.xlsx' because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file."
Any ideas on how to use the createReadStream more effectively to do this and preserve the .xlsx format?
I don't think the saveAs method will work since this code is being executed in an Azure Function with no access to a local known path.
My first thought was the content type was not right, so I set that, but it still did not work. I tried a UTF-8 encoder but that also did not work.
//const data = await streamToText(download_csv.createReadStream())
const download_reader = await download_csv.createReadStream();
let data = '';
for await (const chunk of download_reader) {
data += chunk; //---I suspect I need to do something different here
}
// const data_utf8 = utf8.encode(data) //unescape( encodeURIComponent(data) );
const AZURE_STORAGE_CONNECTION_STRING = "..." //---Removed string here
// Create the BlobServiceClient object which will be used to create a container client
const blob_service_client = BlobServiceClient.fromConnectionString(AZURE_STORAGE_CONNECTION_STRING);
// Get a reference to a container
const container_client = blob_service_client.getContainerClient('order');
const blob_name = 'order_copy.xlsx';
// Get a block blob client
const block_blob_client = container_client.getBlockBlobClient(blob_name);
const contentType = 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
const blobOptions = { blobHTTPHeaders: { blobContentType: contentType } };
//const uploadBlobResponse = await block_blob_client.upload(data_utf8, data_utf8.length, blobOptions);
const uploadBlobResponse = await block_blob_client.upload(data, data.length, blobOptions);
console.log("Blob was uploaded successfully. requestId: ", uploadBlobResponse.requestId);
Any guidance would be appreciated. Thank you in advance for your help!
-Chad
Thanks #Gaurav for the suggestion on not setting the data to a string. The following code worked after I changed to using a array of the chunks and concatenated it using the Buffer similar to your suggested code.
let chunks = []
for await (const chunk of download_reader) {
chunks.push(chunk)
}
const fileBuffer = Buffer.concat(chunks)
...
const uploadBlobResponse = await block_blob_client.upload(fileBuffer, fileBuffer.length, blobOptions);
Thanks everyone!

Use gunzip on a folder

Right so I have a folder full of other folders, which are compressed into .gz files. Inside these folders is text files.
I want to have a program that loops through these text files to see if they contain a specific string, but to do so I need to uncompress them first. I don't want to start messing about with files (unless I can just make them temporarily and delete after), i just want to perform operations on the contents of the .gz folder. I've tried zlib.Gunzip()._outBuffer.toString() which gives a load of gibberish when used on a compressed folder.
How should I proceed?
Had to to something quite similar recently, here's what worked for me:
Basically you just read in the file into a buffer which you then can pass to the gunzip function. This will return another buffer on which you can invoke toString('utf8') in order the get the contents as a string, which is exactly what you need:
const util = require('util');
let {gunzip} = require('zlib');
const fs = require('fs');
gunzip = util.promisify(gunzip);
async function getStringFromGzipFile(inputFilePath) {
const sourceBuffer = await fs.promises.readFile(inputFilePath);
return await gunzip(sourceBuffer);
}
(async () => {
const stringContent = await getStringFromGzipFile('/path/to/file');
console.log(stringContent);
})()
EDIT:
If you want to gunzip and extract a directory, you can use tar-fs which will extract the contents to a specified directory. Once your done processing the files in it you could just remove the directory. Here's how you would gunzip and extract a .tar.gz:
function gunzipFolder(sourceDir, destination) {
fs.createReadStream(sourceDir)
.pipe(zlib.createGunzip())
.pipe(tar.extract(destination));
}

is there are any ways to merge pdf docs into one pdf file(this file should consists from one pdf page as well)

I have several pdf docs for example 4, and I need merge them into 1 pdf file. I was trying to use merge-pdf but documentation for this package is lean, so I got my merged pdf's but it merged into several pages. I should probably use hummus.js or another package, but I'm not sure. Any help?
You can do this on any computer using a free online PDF merger called PDF Joiner, or you can use a free app called PDF Creator on Windows or the built-in Preview program on Mac.
or you can convert it by yourself by using copying content of all pdfs into doc file and save this doc file as pdf
You can use HummusJS for this purpose, here's an example of combining three PDF files. One might want to improve error handling / corner cases etc. but this certainly does the job.
const fs = require("fs")
const hummus = require("hummus");
const memoryStreams = require("memory-streams");
// Combine PDF files into one buffer.
function combinePDFs(...filePaths) {
const pdfBuffers = filePaths.map(filePath => fs.readFileSync(filePath));
const resultStream = new memoryStreams.WritableStream();
const writer = hummus.createWriterToModify(new hummus.PDFRStreamForBuffer(pdfBuffers[0]), new hummus.PDFStreamForResponse(resultStream));
// Add the subsequent files
pdfBuffers.slice(1).forEach(buffer => {
writer.appendPDFPagesFromPDF(new hummus.PDFRStreamForBuffer(buffer));
});
writer.end();
resultStream.end();
return resultStream.toBuffer();
};
const resultBuffer = combinePDFs("pdf1.pdf", "pdf2.pdf", "pdf3.pdf");
fs.writeFileSync("result.pdf", resultBuffer);

Javascript create zip file

I am developing a website using react.js and admin-on-rest. One feature is allowing users to upload a pdf file.
I get the file as type FILE and want to get the file from FILE, compress it to zip, and then make it to type FILE.
So it should be FILE -> origin file -> zip file -> FILE from zip file.
I tried JSZip but still can not figure it out.
Any help is appreciated. Thanks
You can use JSZIP.
**use npm to install JSZIP
let zip = require('jszip')();
//hoping you have already taken input
let input = document.getElementById('fileInput'); // fileInput is id of my input element
let file = input.files[0];
let allZip = zip.file(file.name, file);
console.log(allZip)
Hi Garrick following are the steps you need to take.
1) handle fileupload in a rest wrapper
https://marmelab.com/admin-on-rest/RestClients.html#decorating-your-rest-client-example-of-file-upload
the above example is for image upload. But you will essentially be doing the same thing.
2)
const addUploadCapabilities = requestHandler => (type, resource, params) => {
if (type === 'UPDATE' && resource === 'posts') {
//use jszip to zip file here and package it however you need
// call the API with zipped file
} return requestHandler(type, resource, params);
};
There is a small app called jszip for this. Try, it would help. https://stuk.github.io/jszip/

Convert ICO icon file to PNG image file using plain Javascript

I want to..
.. convert an ICO file (e.g. http://www.google.com/favicon.ico ) to a PNG file after I downloaded it.
.. preserve transparency.
.. apply the solution in a node.js application.
I don't want to and already tried to ..
.. use native tools such as imagemagick (that's what I currently use in my application, but it's really bad for maintaining platform independency).
.. use tools that internally use native tools (e.g. gm.js).
.. rely on webservices such as http://www.google.com/s2/favicons?domain=www.google.de that don't allow configuring the resulting size or require payments or logins.
Therefore I'd love a Javascript-only solution. I used Jimp in another application, but it does not support ICO files.
Any help is appreciated. Thanks!
Use a FileReader() . Convert the Base64 to a data/png. Done.
const inputFile = __dirname + "/favicon.ico";
const outputFile = __dirname + "/favicon.png";
(function( inputFile, outputFile ) {
const fileApi = require("file-api");
const fs = require("fs");
const File = fileApi.File;
var fileReader = new fileApi.FileReader();
fileReader.readAsDataURL(new File(inputFile));
fileReader.addEventListener("load", function (ev) {
var rawdata = ev.target.result;
rawdata = rawdata.replace(/.*base64,/, "");
fs.writeFileSync(outputFile, rawdata, "base64");
});
})(inputFile, outputFile);
I am not familiar with Node environment but I wrote this ES6 module PNG2ICOjs using purely Javascript ArrayBuffer or Blob and can 100% run on client-side browsers (I assume Node file should act like a Blob).
import { PngIcoConverter } from "../src/png2icojs.js";
// ...
const inputs = [...files].map(file => ({
png: file
}));
// Result is a Blob
const resultBlob1 = await converter.convertToBlobAsync(inputs); // Default mime type is image/x-icon
const resultBlob2 = await converter.convertToBlobAsync(inputs, "image/your-own-mime");
// Result is an Uint8Array
const resultArr = await converter.convertAsync(inputs);

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