Get user-defined variables

user-defined vars.js

var snapshot = {};
for (var k in window) {
  snapshot[k] = window[k]
}


var a = 1;

var diff = {};
for (var k in window) {
  if (window[k] !== snapshot[k]) {
    diff[k] = window[k];
  }
}

console.log(diff)
//    a: 1
// diff: Object