write the binary string into an image file

Question

in php we can write the binary string into an image file by using this

$binary = hex2bin($hex);
file_put_contents("myphoto.png", $binary);

it uses the file_put_contents in order to Write it to disk:

in node.js how can we achieve this like the file_put_contents. ?

EDIT: I tried this as suggested by the comments but it gives me an error

 var binarydata = fs.readFileSync('mybin.txt',{flag:'w'});

        fs.writeFileSync( 'myphoto.png', binarydata );


Error: EPERM, operation not permitted
    at Error (native)
    at Object.fs.readSync (fs.js:552:19)
    at Object.fs.readFileSync (fs.js:389:28)

Thank you in advance.

Reading the documentation for the fs (file system) module would be a good place to start. — Jordan Running
– Jordan Running, Commented May 4, 2015 at 18:18
something like fs.writeFileSync() and making sure what you are writing is a Buffer type — Catalyst
– Catalyst, Commented May 4, 2015 at 18:19

RafaelKr · Accepted Answer · 2015-05-04 19:39:40Z

4

This should work for you:

var fs = require( 'fs' );
var wstream = fs.createWriteStream( 'myphoto.jpg' );
wstream.write( $binary );
wstream.end();

Here is the documentation for node.js fs-module: https://nodejs.org/api/fs.html

If you want to do something when it has finished use

fs.writeFileSync( 'myphoto.png', $binary );

or do it asynchronous:

var fs = require('fs');
var wstream = fs.createWriteStream('myphoto.jpg');
wstream.on( 'finish', function() {
    // do something
});
wstream.write( $binary );
wstream.end();

Read file and write to another file:

var fs = require('fs');
fs.readFile( 'temp.txt', function( err, data ) {
    if (err) throw err;

    var wstream = fs.createWriteStream( 'myphoto.jpg' );
    wstream.on( 'finish', function() {
        // do something
    });
    wstream.write( data );
    wstream.end();
});

Edit: My code was working all time, it just has to be 'myphoto.jpg' instead of 'myphoto.png' ;) So the solution isn't to do it like this, you just have to rename the file:

var fs = require('fs');
fs.renameSync( 'temp.txt', 'myphoto.jpg' );

or if you need your temp.txt, then copy it like this:

var fs = require('fs');
fs.createReadStream( 'temp.txt' ).pipe( fs.createWriteStream( 'myphoto.jpg' ) );

edited May 4, 2015 at 19:39

answered May 4, 2015 at 18:21

RafaelKr

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7 Comments

jemz Over a year ago

my binary data is stored in a file temp.txt,how can I get it first ?

RafaelKr Over a year ago

Please read the documentation... fs.readFileSync( 'temp.txt' ); I'll also edit my post to add an asynchronous codesnippet to my post, then you should know all you need

jemz Over a year ago

Error: EPERM, operation not permitted

RafaelKr Over a year ago

Do you use Linux? Then start node with sudo

jemz Over a year ago

im in windows...I tried your code. but the image cannot be open

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