JSON.stringify returns ” instead of “”

I’m looking to turn text like this into JSON:

Company     Team
Facebook    Marketing
Google      Engineering
Microsoft   Product

When I log the JSON.stringify returns " instead of ". Why does that happen? What can I change to prevent this?

let pre = document.querySelector('pre').innerHTML;

var cells = pre.split('n').map(function (el) { return el.split(/s+/); });

var headings = cells.shift();

var obj = cells.map(function (el) {
  var obj = {};
  for (var i = 0, l = el.length; i < l; i++) {
    obj[headings[i]] = isNaN(Number(el[i])) ? el[i] : +el[i];
  }
  return obj;
});


var json = JSON.stringify(obj,null,5);
console.log(json)

JS Fiddle