What will log? Part I

wwl.js

var people = (function() {
  var people = [];

  render();

  function render() {
    var people = people;
    console.log(people);
  }
}())

It's undefined because of what's known as "hoisting" in javascript. When the render function is called, an execution context is created in the execution stack. This happens in 2 phases, the first one being the "creation phase", where the interpreter finds all variable declarations and allocates memory space for them. It also and assigns them the special value undefined. The second phase, called the "execution phase", is when the interpreter actually executes the code and assigns the values. So it will assign the value of people (which is undefined as explained in the "creation phase") to people, so it will be undefined.

Easier said, it's like writing the code as:
var people;
people = people;

yes @ionelh, thank you!