How do I edit a file in pure js (without node)? I get a file with an input field and I read its text like this:

var fileReader = new FileReader();
fileReader.readAsText(file);

fileReader.onload = function () {
    alert(this.result);
}

So, pretty straight forward. I tried to look on the net how to use a fileWriter but with no success. I just need to edit the text inside that file and save it, how can I do?

How do I edit a file in pure js (without node)? I get a file with an input field and I read its text like this:

var fileReader = new FileReader();
fileReader.readAsText(file);

fileReader.onload = function () {
    alert(this.result);
}

So, pretty straight forward. I tried to look on the net how to use a fileWriter but with no success. I just need to edit the text inside that file and save it, how can I do?

• javascript
• filereader
• filewriter

2 Answers 2

You can read in the data in the text file, modify it in client side JavaScript (no Node), and then output and re-save it. It does require user interaction, though.

This is a JS fiddle I modified that outputs the file from some text, although it does no reading of files.

Originally taken from this Stackoverflow question

(function () {
    var textFile = null;
  function makeTextFile(text) {
    var data = new Blob([text], {type: 'text/plain'});

    // If we are replacing a previously generated file we need to
    // manually revoke the object URL to avoid memory leaks.
    if (textFile !== null) {
      window.URL.revokeObjectURL(textFile);
    }

    textFile = window.URL.createObjectURL(data);

    return textFile;
  }


  var create = document.getElementById('create');
  var textbox = document.getElementById('textbox');

    //create a click event listener
  create.addEventListener('click', function () {
    var link = document.getElementById('downloadlink');
    link.setAttribute('download', 'info.txt');
    //make the text file
    link.href = makeTextFile(textbox.value);
    link.style.display = 'block';
        //wait for the link to be rendered and then initiate a click to download the file
     window.requestAnimationFrame(function () {
      var event = new MouseEvent('click');
      link.dispatchEvent(event);
      document.body.removeChild(link);
    });
  }, false);

})();

You can't write files in a browser, you'll have to use node.