JavaScript Code Examples

example_1.js

// Question: Explain the difference in how x is defined in these three examples

// Sample A
function a(){
  x = 1;
}

// Sample B
function b(){
  var x = 1;
}

// Sample C
x = 2;
function c(){
  var x = 1;
}

example_2.js

// Question: In what order will the strings be printed to the console when this file is executed?

// Assume fetch is a function that requests a URL and returns a Promise
function fetchData() {
  return fetch('/data').then(function() {
    console.log('a');
  });
}

console.log('c');

fetchData().then(function() {
  console.log('d');
});

console.log('b');

example_3.js

// User Constructor
function User(){
  this.getName = function(){}; 
}

// Task Constructor
function Task(){}
Task.prototype.getSummary = function(){};

var user = new User();
var task = new Task();

// Question: What is the result of these console statements? Why is this the case?
console.log(user.hasOwnProperty('getName'));
console.log(task.hasOwnProperty('getSummary'));