• JavaScript library designed to simplify the client-side scripting of HTML
  
• free
• open source

• $("#idElement): elements with the specified id 
  
• $(".className): element with the specified className
  
• $("#idElement .className)
  
• $("[attribute='value']")
  
• $(":first-child")
  

• element.addClass()
  
• element.removeClass()
  
• element.attr("attributeName")
  
• element.attr("attributeName", "attributeValue")
  
• element.html()
  
• element.html(htmlString)
  
• element.empty()
  
• element.hide()
  
• element.show()
  

• element.click( handler(eventObject) );
  

 $("#idElement").click(function(event) {
   alert("click");
 });

• asynchronous web applications
  
• Jquery has a full suite of AJAX capabilities
  

•  var request = $.ajax( "example.html" )
      .done(function() { alert("success"); })
      .fail(function() { alert("error"); })
      .always(function() { alert("complete"); });

• JavaScript Object Notation
  
• like Javascript Objects
  

 {
    "firstName": "John",
    "lastName": "Smith",
    "age": 25,
    "address": {
        "streetAddress": "21 2nd Street",
        "city": "New York",
        "state": "NY",
        "postalCode": "10021"
    },
    "phoneNumber": [
        {
            "type": "home",
            "number": "212 555-1234"
        },
        {
            "type": "fax",
            "number": "646 555-4567"
        }
    ]
}