HTML5 FileReader equivalent for nodejs 'fs'

Question

I was trying to read and write a file in javascript. Nodejs 'fs'is not working. I came to know that there is an equivalent HTML5 API's.

What is the equivalent for

fs.writeFile('my.file', filedata)
fs.readFileSync(__dirname + '/dir/leaves.file')

in HTML5 filereader api

Answer 1

There is no* fs equivalent in web APIs, for obvious security reasons.

fs -> filesystem, and browsers won't give access to the user's filesystem to any random script on the web.

• You can read files with a FileReader,
• you can load files from a server with XHR, or you can ask your user to give you files from their filesystem,
• and you can prompt your user to save files.

But none of these operations will be done directly from the user's file-system, without his own action.

(*Actually we could consider IndexedDB and alike as filesystems, but they can't be compared to fs either...)

Answer 2

You can load files using the FileReader like so:

var openFile = function(event) {
    var input = event.target;

    var reader = new FileReader();
    reader.onload = function(){
        var dataURL = reader.result;
        var output = document.getElementById('output');
        output.src = dataURL;
    };
    reader.readAsDataURL(input.files[0]);
};

<input type='file' accept='image/*' onchange='openFile(event)'><br>
<img id='output'>