npm install acorn-globals

js
var fs = require('fs');
var detect = require('acorn-globals');

var src = fs.readFileSync(__dirname + '/input.js', 'utf8');

var scope = detect(src);
console.dir(scope);

js
var x = 5;
var y = 3, z = 2;

w.foo();
w = 2;

RAWR=444;
RAWR.foo();

BLARG=3;

foo(function () {
    var BAR = 3;
    process.nextTick(function (ZZZZZZZZZZZZ) {
        console.log('beep boop');
        var xyz = 4;
        x += 10;
        x.zzzzzz;
        ZZZ=6;
    });
    function doom () {
    }
    ZZZ.foo();

});

console.log(xyz);

$ node example/detect.js
[ { name: 'BLARG', nodes: [ [Object] ] },
  { name: 'RAWR', nodes: [ [Object], [Object] ] },
  { name: 'ZZZ', nodes: [ [Object], [Object] ] },
  { name: 'console', nodes: [ [Object], [Object] ] },
  { name: 'foo', nodes: [ [Object] ] },
  { name: 'process', nodes: [ [Object] ] },
  { name: 'w', nodes: [ [Object], [Object] ] },
  { name: 'xyz', nodes: [ [Object] ] } ]