JS fundamental questions

interview.js

/**
 * The following examples help ensure understanding of some JavaScript fundamentals.
 * Please make sure you understand these prior to the interview. Deep knowledge of JS is
 * not required for the interview, but these fundamentals are.
 *
 * The third and final example is less about JS fundamentals, and is simply to show an
 * example of using recursion. One interview question will involve recursion.
 *
 * You can try out running this code in your browser by opening the JavaScript console.
 * Open developer tools and go to console. On some browsers/OS you can do ctrl+shift+j.
 */

/**
 * Example 1
 * ---------
 * For understanding how variables are passed to functions, make sure you understand 
 * why one variable did not change and the others did.
 */
var myValue = 1;
var myRef = { a: 'Three Body Problem' };
function test(param1, param2) {
  console.log('param1 = ' + param1);
  console.log('myValue = ' + myValue);
  console.log('param2 = ', param2);
  console.log('myRef = ', myRef);
  param1 = 'something new';
  param2.a = 'A Memory Called Empire';
  console.log('param1 = ' + param1); // changed
  console.log('myValue = ' + myValue); // did not change, primitives (strings, numbers) are passed by value
  console.log('param2 = ', param2); // changed
  console.log('myRef = ', myRef); // changed, objects are passed by reference
  return 'done';
}
console.log(test(myValue, myRef));

/**
 * Example 2
 * ---------
 * For understanding how arrays and objects work, this code shows how to access
 * and set values in arrays and objects.
 */
var myArray = [
  'zeroth',
  'first',
  'second',
  { a: 'pineapple' }
];
var myObj = {
  prop1: 'apple',
  prop2: 'banana',
  prop3: { subProp1: myArray }
};

console.log(myArray[0]); // prints 'zeroth'
console.log(myArray[3].a); // prints 'pineapple'
console.log(myObj.prop1); // prints 'apple'
console.log(myObj['prop1']); // also prints 'apple'
console.log(myObj.prop3.subProp1[3].a); // prints 'pineapple'
myObj.prop3.subProp1[3].somethingNew = 'mango';
console.log(myArray[3].somethingNew); // prints 'mango'

/*
 * Example 3
 * ---------
 * This shows how recursion works. This isn't really a JS-specific thing, but it is important
 * that you understand it for the interview.
 */
var myDeepObject = {
  prop: {
    prop: {
      prop: {
        prop: {
          prop: {
            prop: 'aardvark'
          }
        }
      }
    }
  }
};
var myShallowObject = {
  prop: 'binturong' 
};
function findAnimal(x) {
  if (typeof x === 'string') {
    return x;
  }
  return findAnimal(x.prop);
}
console.log(findAnimal(myDeepObject)); // prints 'aardvark'
console.log(findAnimal(myShallowObject)); // prints 'binturong'