Introduction to Javascript

The code that we ran above:

    // variable scope with and without var:
  var n = 2;
  m = 5;
  function f() {
  document.write("n =  " + n + "<br />");
  document.write("m =  " + m + "<br />");
  var n = 3;
  m = 6;
  document.write("n =  " + n + "<br />");
  document.write("m =  " + m + "<br />");
  }
  f();
  document.write("n =  " + n + "<br />");
  document.write("m =  " + m + "<br />");

  // functions are first-class
  function g1(n) {
  return n + 1;
  }

  document.write("g1 is a function: " + g1 + "<br />");
  document.write("g1(2) = " + g1(2) + "<br />");
  
  g2 = function(n) {
  return n + 1;
  }

  document.write("g2 is a function: " + g2 + "<br />");
  document.write("g2(2) = " + g2(2) + "<br />");

  // higher-order functions:
  function h(g, n) {
  return g(g(n));
  }

  document.write("h(g1, 3) = " + h(g1,3) + "<br />");  

  document.write("h.name = " + h.name + "<br />");
  // the number of arguments
  document.write("h.length = " + h.length + "<br />");

  // Javascript objects:
  var person = {firstName:"Mary", lastName:"Smith", DOB:1997, eyeColor:"blue"};
  document.write("name = " + person.firstName + " " + person.lastName + "<br />");
  document.write("name = " + person['firstName'] + " " + person['lastName'] + "<br />");

  person.location = "Morris";
  document.write("name = " + person.firstName + " lives in " + person.location + "<br />");
  person.moveTo = function(newPlace) {this.location = newPlace};

  person.moveTo("New York");
  document.write("name = " + person.firstName + " lives in " + person.location + "<br />");