Javascript Scope

main.js

var x = 5;

function one() {
    console.log("one(): %s", x);
}

function two() {
  console.log("two(): %s", x);
  var x;
}


function three(cb) {
  console.log("three(): %s", x);
  var x = 4;
  cb();
}

one();  // one(): 5
two();  // two(): undefined
three(one);  // three(): undefined, one(): 5