Storing into file using JavaScript/GreaseMonkey

Question

I have captured list of data from the page using Greasemonkey.

GM Script

var hit = GM_getValue("hit") || 0;
var _url = "http://localhost:8080/test?p=$$pageNo$$";
_url = _url.replace("$$pageNo$$", hit);
GM_setValue("hit", ++hit); 
if(hit <= 100) {
window.location.href = _url;
}

This script will runs for nth time and capture <10K data, now i facing the issue in storing the captured data in some file. Anyone has any idea about how we can store the captured data into file/repo?

Thanks - Viswanathan G

Answer 1

A very fast and easy solution is to use FileSaver.js :
1) Add the following line into the ==UserScript== section of your Greasemonkey script

// @require     https://raw.githubusercontent.com/eligrey/FileSaver.js/master/FileSaver.js

2) Add the 2 following lines of code to the GM script

var blob = new Blob(["Hello, world!"], {type: "text/plain;charset=utf-8"});

saveAs(blob, "hello world.txt");

This code example will display a dialog box to download a file named "hello world.txt" containing the text "Hello, world!". Just replace this by the file name and the text content of your choice !

Answer 2

Nope, can't write it to a file, but if you're really bored, you can post it to http://pastebin.com (or any other URL that accepts a POST request with a bunch of data).

GM_xmlhttpRequest({
  method: "POST",
  url: "http://pastebin.com/post.php",
  data: <your data here>,
  headers: {
    "Content-Type": "application/x-www-form-urlencoded"
  },
  onload: function(response) {
    alert("posted");
  }
});

Note you need to have a pastebin account to use the API.

---

If you really need to write a file to your local filesystem, run a web server on your desktop, and then save the results of an http PUT request to disk.

Answer 3

I use this trick to download a file from a Tampermonkey script:

var saveData = (function () {
    var a = document.createElement("a");
    document.body.appendChild(a);
    a.style = "display: none";
    return function (data, fileName) {
        var blob = new Blob([data], {type: "octet/stream"});
        var url = window.URL.createObjectURL(blob);
        a.href = url;
        a.download = fileName;
        a.click();
        window.URL.revokeObjectURL(url);
    };
}());

Then call it with:

saveData("this data will be written in the file", "file.txt");

It works by creating a hidden element and simulating that element being clicked. It will behave as if the user clicked a download link, so the file will be downloaded by the browser, and saved wherever the browser puts downloaded files.

Answer 4

Yes , you can write to a file. But not everywhere in the system, for obvious security reasons, you can just write in cookies directory

  var cookie_name="YourCookie";
  var cookie_value="What you want to save inside your cookie";
  var d = new Date();
  d.setTime(d.getTime() + (28*24*60*60*1000));
  var expires = "expires="+ d.toUTCString();
  document.cookie = cookie_name +"=" + cookie_value + ";" + expires + ";path=/";

You can then

• script a filecopy from cookie directory to your desktop, depending on your OS

• or read value from Chrome Inspect -> Application -> Cookies

• or retrieving the Cookie and print it in console with

  decodeURIComponent(document.cookie);