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

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

• javascript
• html
• filereader
• html5-filesystem

Share Improve this question Follow asked Aug 30, 2017 at 6:23 SibirajSibiraj 4,76688 gold badges3737 silver badges5959 bronze badges 4

• You are looking for the FileReader: developer.mozilla/en-US/docs/Web/API/FileReader – Get Off My Lawn Commented Aug 30, 2017 at 6:24
• can you tell me an exact equivalent? I am little confused @GetOffMyLawn – Sibiraj Commented Aug 30, 2017 at 6:29
• 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 f-s, 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 action. (*well actually we could consider IndexedDB and alike as filesystems...) – Kaiido Commented Aug 30, 2017 at 7:41
• @Kaiido . Can you post that as an answer? I will close this question. – Sibiraj Commented Oct 30, 2017 at 5:25

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2 Answers 2

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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 pared to fs either...)

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'>