Using Google Chrome extensions to import/export JSON files?

Question

I'm creating a Google Chrome extension at the moment and I was wondering if it's possible for it to both create JSON files to download (export) and create a button where users can make the extension open and parse JSON files that they have saved in their local file system or on a USB stick (import)?

The parsing of each JSON from the local file system would simply involve reading off each key-value pair and doing something with the data. It would only have to deal with strings, so nothing complicated.

**EDIT: **My question is not a duplicate of this one because I'm not interested in changing the user's download path. All I want is to enable them to, with their consent, download a file to their normal download directory (which Filesaver.js can do). Plus, that post says nothing about importing.

Answer 1

You can fake link to "download" imaginary array MyData or whatever,:

var MyArray = [elem1, elem2, ....];
var _myArray = JSON.stringify(MyArray , null, 4); //indentation in json format, human readable

var vLink = document.createElement('a'),
vBlob = new Blob([_myArray], {type: "octet/stream"}),
vName = 'watever_you_like_to_call_it.json',
vUrl = window.URL.createObjectURL(vBlob);
vLink.setAttribute('href', vUrl);
vLink.setAttribute('download', vName );
vLink.click();

this will export/download your array into json file named as vName variable.

---

If you wish to import/read file:
create input element (type=file) and make it invisible (here I'm having html element and then adding js listener in script)

<input type="file" id="importOrig" accept=".json" style="display:none"/>

script

importOrig.addEventListener("change", importFun, false);

make button fakeImp (or any element), that you can style as you wish and that will be used as trigger for importing event

fakeImp.onclick = function () {importOrig.click()}

import function (from listener)

function importFun(e) {
  var files = e.target.files, reader = new FileReader();
  reader.onload = _imp;
  reader.readAsText(files[0]);
}

function _imp() {
  var _myImportedData = JSON.parse(this.result);
  //here is your imported data, and from here you should know what to do with it (save it to some storage, etc.)

  ......
  importOrig.value = ''; //make sure to clear input value after every import
}