• Javascript is not JAVA ! 
  
• interpreted computer programming language
  
• JavaScript is a prototype-based scripting language that is dynamic
  
• web browsers
• ECMAScript
  

var x; //defines the variable x, although no value is assigned to it by default
var y = 2; //defines the variable y and assigns the value of 2 to it
var z = "String";

• keyword function
  

function add(a, b) {
  return a + b;
}
var c = add(2,3);

•  Object properties
  

var text = "javascript is cool";
var a = text["length"];
var b = text.length;

• Define your own objects

var cat = {colour: "grey", name: "Bogdan"};
delete cat.colour;
var colour = cat.colour;

• Adding methods to an object

• String

 var txt = "string"; charAt() : Returns the character at the specified index
 indexOf() : Returns the position of the first found occurrence of a specified value in a string
 toLowerCase() : Converts a string to lowercase letters
 toUpperCase() : Converts a string to uppercase letters

function People(name, age) {
  this.name = name;
  this.age = age;
  this.speak = function() {
     return "I am a person";
  };
}
var bogdan = new People("Bogdan", 23);
var andrei = new People("Andrei", 18);
bogdan.speak();

• Placing JavaScript in your pages

 <script>
function myFunction() {}
</script>

• represents an open window in a browser. 
  

window.alert("Hello"); Displays an alert box with the message "Hello" and an OK button
window.confirm("Confirm"); Displays a dialog box with a message and an OK and a Cancel button
window.close(); Closes the current window

• each HTML document loaded into a browser

document.write("Hello World!"); 
var a = "test";
document.write(a);

document.title; Return the title of the document; 

• searching for elements in DOM 

 document.getElementById(id)

• changing HTML Content
  

 document.getElementById(id).innerHTML = new HTML; var htmlText = document.getElementById(id).innerHTML;

• changing element attribute
  

 document.getElementById(id).attribute = new value; var attributeValue = document.getElementById(id).attribute;

• an event occurs when something happens in a browser window
  
• html event attributes

• onclick - Fires on a mouse click on the element
  onblur - Fires the moment that the element loses focus
  onchange - Fires the moment when the value of the element is changed
  onload	- Fires after the page is finished loading